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  • Kinetics  (414)
  • American Association for the Advancement of Science (AAAS)  (414)
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  • American Association for the Advancement of Science (AAAS)  (414)
  • American Chemical Society
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  • National Academy of Sciences
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  • 1
    Publication Date: 1998-04-16
    Description: Photoactive yellow protein (PYP) is a member of the xanthopsin family of eubacterial blue-light photoreceptors. On absorption of light, PYP enters a photocycle that ultimately transduces the energy contained in a light signal into an altered biological response. Nanosecond time-resolved x-ray crystallography was used to determine the structure of the short-lived, red-shifted, intermediate state denoted [pR], which develops within 1 nanosecond after photoelectronic excitation of the chromophore of PYP by absorption of light. The resulting structural model demonstrates that the [pR] state possesses the cis conformation of the 4-hydroxyl cinnamic thioester chromophore, and that the process of trans to cis isomerization is accompanied by the specific formation of new hydrogen bonds that replace those broken upon excitation of the chromophore. Regions of flexibility that compose the chromophore-binding pocket serve to lower the activation energy barrier between the dark state, denoted pG, and [pR], and help initiate entrance into the photocycle. Direct structural evidence is provided for the initial processes of transduction of light energy, which ultimately translate into a physiological signal.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Perman, B -- Srajer, V -- Ren, Z -- Teng, T -- Pradervand, C -- Ursby, T -- Bourgeois, D -- Schotte, F -- Wulff, M -- Kort, R -- Hellingwerf, K -- Moffat, K -- New York, N.Y. -- Science. 1998 Mar 20;279(5358):1946-50.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9506946" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*chemistry/metabolism ; Chromatiaceae/chemistry ; Crystallography, X-Ray ; Energy Metabolism ; Fourier Analysis ; Hydrogen Bonding ; Isomerism ; Kinetics ; *Light ; Models, Molecular ; *Photoreceptors, Microbial ; *Protein Conformation ; Signal Transduction
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-02-19
    Description: A single kinesin molecule can move "processively" along a microtubule for more than 1 micrometer before detaching from it. The prevailing explanation for this processive movement is the "walking model," which envisions that each of two motor domains (heads) of the kinesin molecule binds coordinately to the microtubule. This implies that each kinesin molecule must have two heads to "walk" and that a single-headed kinesin could not move processively. Here, a motor-domain construct of KIF1A, a single-headed kinesin superfamily protein, was shown to move processively along the microtubule for more than 1 micrometer. The movement along the microtubules was stochastic and fitted a biased Brownian-movement model.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Okada, Y -- Hirokawa, N -- New York, N.Y. -- Science. 1999 Feb 19;283(5405):1152-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Tokyo 113-0033, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10024239" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Amino Acid Sequence ; Animals ; Catalytic Domain ; Diffusion ; Drosophila ; Kinesin/chemistry/*metabolism ; Kinetics ; Microscopy, Fluorescence ; Microtubules/*metabolism ; Models, Chemical ; Molecular Motor Proteins/chemistry/*metabolism ; Molecular Sequence Data ; Nerve Tissue Proteins/chemistry/*metabolism ; Recombinant Fusion Proteins ; Stochastic Processes ; Thermodynamics
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  • 3
    Publication Date: 1999-01-08
    Description: Cochlear frequency selectivity in lower vertebrates arises in part from electrical tuning intrinsic to the sensory hair cells. The resonant frequency is determined largely by the gating kinetics of calcium-activated potassium (BK) channels encoded by the slo gene. Alternative splicing of slo from chick cochlea generated kinetically distinct BK channels. Combination with accessory beta subunits slowed the gating kinetics of alpha splice variants but preserved relative differences between them. In situ hybridization showed that the beta subunit is preferentially expressed by low-frequency (apical) hair cells in the avian cochlea. Interaction of beta with alpha splice variants could provide the kinetic range needed for electrical tuning of cochlear hair cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ramanathan, K -- Michael, T H -- Jiang, G J -- Hiel, H -- Fuchs, P A -- DC00276/DC/NIDCD NIH HHS/ -- New York, N.Y. -- Science. 1999 Jan 8;283(5399):215-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Hearing Sciences, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9880252" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing ; Animals ; Calcium/metabolism ; Cell Line ; Electrophysiology ; Gene Expression ; Hair Cells, Auditory/*physiology ; Humans ; In Situ Hybridization ; *Ion Channel Gating ; Kinetics ; Large-Conductance Calcium-Activated Potassium Channel beta Subunits ; Large-Conductance Calcium-Activated Potassium Channels ; Membrane Potentials ; Patch-Clamp Techniques ; Potassium Channels/genetics/*physiology ; *Potassium Channels, Calcium-Activated ; Quail ; RNA, Messenger/genetics/metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Transfection
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-05-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koshland, D E Jr -- New York, N.Y. -- Science. 1998 May 8;280(5365):852-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. dek@uclink4.berkeley.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9599157" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium-Calmodulin-Dependent Protein Kinases/metabolism ; *Cell Cycle ; Cells/metabolism ; Kinetics ; Ligands ; Oocytes/cytology/enzymology/*metabolism ; Xenopus
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  • 5
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-06-27
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yung, Y L -- Kass, D M -- New York, N.Y. -- Science. 1998 Jun 5;280(5369):1545-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125, USA. yly@mercu1.gps.caltech.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9644019" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; Deuterium/*analysis ; *Extraterrestrial Environment ; Hydrogen/*analysis ; Kinetics ; *Mars ; Oxygen/analysis ; Oxygen Isotopes ; Temperature ; Thermodynamics ; *Water
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  • 6
    Publication Date: 1999-11-24
    Description: Modern functional brain mapping relies on interactions of neuronal electrical activity with the cortical microcirculation. The existence of a highly localized, stimulus-evoked initial deoxygenation has remained a controversy. Here, the activity-dependent oxygen tension changes in the microcirculation were measured directly, using oxygen-dependent phosphorescence quenching of an exogenous indicator. The first event after sensory stimulation was an increase in oxygen consumption, followed by an increase in blood flow. Because oxygen consumption and neuronal activity are colocalized but the delayed blood flow is not, functional magnetic resonance imaging focused on this initial phase will yield much higher spatial resolution, ultimately enabling the noninvasive visualization of fundamental processing modules in the human brain.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vanzetta, I -- Grinvald, A -- New York, N.Y. -- Science. 1999 Nov 19;286(5444):1555-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology, Center for Research of Higher Brain Functions, Weizmann Institute of Science, Rehovot 76100, Israel.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10567261" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blood Volume ; Brain Mapping ; Cats ; Cerebrovascular Circulation ; Hemoglobins/analysis ; Humans ; Kinetics ; Luminescence ; Magnetic Resonance Imaging ; Microcirculation ; Neuroglia/metabolism ; Neurons/metabolism ; Oxygen/*blood ; *Oxygen Consumption ; Oxyhemoglobins/analysis ; Photic Stimulation ; Spectrum Analysis ; Visual Cortex/blood supply/*metabolism
    Print ISSN: 0036-8075
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-08-07
    Description: Circadian rhythms control many physiological activities. The environmental entrainment of rhythms involves the immediate responses of clock components. Levels of the clock protein FRQ were measured in Neurospora at various temperatures; at higher temperatures, the amount of FRQ oscillated around higher levels. Absolute FRQ amounts thus identified different times at different temperatures, so temperature shifts corresponded to shifts in clock time without immediate synthesis or turnover of components. Moderate temperature changes could dominate light-to-dark shifts in the influence of circadian timing. Temperature regulation of clock components could explain temperature resetting of rhythms and how single transitions can initiate rhythmicity from characteristic circadian phases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, Y -- Merrow, M -- Loros, J J -- Dunlap, J C -- GM34985/GM/NIGMS NIH HHS/ -- MH01186/MH/NIMH NIH HHS/ -- MH44651/MH/NIMH NIH HHS/ -- New York, N.Y. -- Science. 1998 Aug 7;281(5378):825-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755-3844, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9694654" target="_blank"〉PubMed〈/a〉
    Keywords: Biological Clocks/*physiology ; Blotting, Northern ; *Circadian Rhythm ; Darkness ; Fungal Proteins/biosynthesis/genetics/*metabolism ; Immunoblotting ; Kinetics ; Light ; Neurospora/genetics/metabolism/*physiology ; RNA, Fungal/genetics/metabolism ; RNA, Messenger/genetics/metabolism ; Temperature
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  • 8
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-01-15
    Description: Fluorescent analogs of adenine that selectively oxidize guanine were used to investigate photoinduced electron transfer through the DNA pi-stack as a function of reactant stacking and energetics. Small variations in these factors led to profound changes in the kinetics and distance dependences of DNA-mediated electron-transfer reactions. Values of beta, a parameter reflecting the dependence of electron transfer on distance, ranged from 0.1 to 1.0 per angstrom. Strong stacking interactions result in the fastest electron-transfer kinetics. Electrons are thus transported preferentially through an intrastrand rather than interstrand pathway. Reactant energetics also modulate the distance dependence of DNA-mediated charge transport. These studies may resolve the range of disparate results previously reported, and paradigms must now be developed to describe these properties of the DNA pi-stack, which can range from insulator- to "wire"-like.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kelley, S O -- Barton, J K -- GM49216/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Jan 15;283(5400):375-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Beckman Institute, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9888851" target="_blank"〉PubMed〈/a〉
    Keywords: 2-Aminopurine/chemistry ; Adenine/analogs & derivatives/chemistry ; Base Pairing ; DNA/*chemistry ; *Electrons ; Guanine/chemistry ; Hydrogen Bonding ; Kinetics ; Light ; Nucleic Acid Conformation ; Oxidation-Reduction ; Spectrometry, Fluorescence ; Thermodynamics
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  • 9
    Publication Date: 1999-11-13
    Description: Control of messenger RNA (mRNA) stability serves as an important mechanism for regulating gene expression. Analysis of Arabidopsis mutants that overaccumulate soluble methionine (Met) revealed that the gene for cystathionine gamma-synthase (CGS), the key enzyme in Met biosynthesis, is regulated at the level of mRNA stability. Transfection experiments with wild-type and mutant forms of the CGS gene suggest that an amino acid sequence encoded by the first exon of CGS acts in cis to destabilize its own mRNA in a process that is activated by Met or one of its metabolites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chiba, Y -- Ishikawa, M -- Kijima, F -- Tyson, R H -- Kim, J -- Yamamoto, A -- Nambara, E -- Leustek, T -- Wallsgrove, R M -- Naito, S -- New York, N.Y. -- Science. 1999 Nov 12;286(5443):1371-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10558994" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Arabidopsis/*enzymology/genetics ; Carbon-Oxygen Lyases/chemistry/*genetics/metabolism ; Exons ; Gene Expression Regulation, Enzymologic ; *Gene Expression Regulation, Plant ; Genes, Plant ; Genes, Reporter ; Kinetics ; Methionine/metabolism ; Molecular Sequence Data ; Mutation ; RNA, Messenger/genetics/*metabolism ; Sequence Alignment ; Transcription, Genetic ; Transfection
    Print ISSN: 0036-8075
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  • 10
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-12-04
    Description: Enzymatic turnovers of single cholesterol oxidase molecules were observed in real time by monitoring the emission from the enzyme's fluorescent active site, flavin adenine dinucleotide (FAD). Statistical analyses of single-molecule trajectories revealed a significant and slow fluctuation in the rate of cholesterol oxidation by FAD. The static disorder and dynamic disorder of reaction rates, which are essentially indistinguishable in ensemble-averaged experiments, were determined separately by the real-time single-molecule approach. A molecular memory phenomenon, in which an enzymatic turnover was not independent of its previous turnovers because of a slow fluctuation of protein conformation, was evidenced by spontaneous spectral fluctuation of FAD.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lu, H P -- Xun, L -- Xie, X S -- New York, N.Y. -- Science. 1998 Dec 4;282(5395):1877-82.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Pacific Northwest National Laboratory, William R. Wiley Environmental Molecular Sciences Laboratory, Richland, WA 99352, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9836635" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Brevibacterium/enzymology ; Cholesterol/*metabolism ; Cholesterol Oxidase/*metabolism ; Flavin-Adenine Dinucleotide/*metabolism ; Kinetics ; Microscopy, Fluorescence ; Oxidation-Reduction ; Probability ; Spectrometry, Fluorescence ; Stochastic Processes
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-01-15
    Description: Many distinct signaling pathways allow the cell to receive, process, and respond to information. Often, components of different pathways interact, resulting in signaling networks. Biochemical signaling networks were constructed with experimentally obtained constants and analyzed by computational methods to understand their role in complex biological processes. These networks exhibit emergent properties such as integration of signals across multiple time scales, generation of distinct outputs depending on input strength and duration, and self-sustaining feedback loops. Feedback can result in bistable behavior with discrete steady-state activities, well-defined input thresholds for transition between states and prolonged signal output, and signal modulation in response to transient stimuli. These properties of signaling networks raise the possibility that information for "learned behavior" of biological systems may be stored within intracellular biochemical reactions that comprise signaling pathways.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bhalla, U S -- Iyengar, R -- GM-54508/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Jan 15;283(5400):381-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Mount Sinai School of Medicine, New York, NY 10029, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9888852" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcineurin/metabolism ; Calcium/metabolism ; Calcium-Calmodulin-Dependent Protein Kinase Type 2 ; Calcium-Calmodulin-Dependent Protein Kinases/metabolism ; *Cell Cycle Proteins ; Computer Simulation ; Cyclic AMP/metabolism ; Dual Specificity Phosphatase 1 ; Enzyme Activation ; Epidermal Growth Factor/pharmacology ; Feedback ; Immediate-Early Proteins/metabolism ; Isoenzymes/metabolism ; Kinetics ; Long-Term Potentiation ; Memory ; *Models, Biological ; Neurons/metabolism ; Phospholipase C gamma ; *Phosphoprotein Phosphatases ; Phosphorylation ; Protein Kinase C/metabolism ; Protein Phosphatase 1 ; Protein Tyrosine Phosphatases/metabolism ; Receptor, Epidermal Growth Factor/metabolism ; Receptors, N-Methyl-D-Aspartate/metabolism ; Second Messenger Systems ; *Signal Transduction ; Synapses/metabolism ; Type C Phospholipases/metabolism
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  • 12
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-06-18
    Description: The enhanced aerodynamic performance of insects results from an interaction of three distinct yet interactive mechanisms: delayed stall, rotational circulation, and wake capture. Delayed stall functions during the translational portions of the stroke, when the wings sweep through the air with a large angle of attack. In contrast, rotational circulation and wake capture generate aerodynamic forces during stroke reversals, when the wings rapidly rotate and change direction. In addition to contributing to the lift required to keep an insect aloft, these two rotational mechanisms provide a potent means by which the animal can modulate the direction and magnitude of flight forces during steering maneuvers. A comprehensive theory incorporating both translational and rotational mechanisms may explain the diverse patterns of wing motion displayed by different species of insects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dickinson, M H -- Lehmann, F O -- Sane, S P -- New York, N.Y. -- Science. 1999 Jun 18;284(5422):1954-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Integrative Biology, University of California, Berkeley, CA 94720, USA. flymannd@socrates.berkeley.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10373107" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Drosophila melanogaster/*physiology ; Flight, Animal/*physiology ; Kinetics ; Models, Biological ; Movement ; Robotics ; Rotation ; Wings, Animal/*physiology
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  • 13
    Publication Date: 1997-11-14
    Description: The sequencing of euryarchaeal genomes has suggested that the essential protein lysyl-transfer RNA (tRNA) synthetase (LysRS) is absent from such organisms. However, a single 62-kilodalton protein with canonical LysRS activity was purified from Methanococcus maripaludis, and the gene that encodes this protein was cloned. The predicted amino acid sequence of M. maripaludis LysRS is similar to open reading frames of unassigned function in both Methanobacterium thermoautotrophicum and Methanococcus jannaschii but is unrelated to canonical LysRS proteins reported in eubacteria, eukaryotes, and the crenarchaeote Sulfolobus solfataricus. The presence of amino acid motifs characteristic of the Rossmann dinucleotide-binding domain identifies M. maripaludis LysRS as a class I aminoacyl-tRNA synthetase, in contrast to the known examples of this enzyme, which are class II synthetases. These data question the concept that the classification of aminoacyl-tRNA synthetases does not vary throughout living systems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ibba, M -- Morgan, S -- Curnow, A W -- Pridmore, D R -- Vothknecht, U C -- Gardner, W -- Lin, W -- Woese, C R -- Soll, D -- New York, N.Y. -- Science. 1997 Nov 7;278(5340):1119-22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, Post Office Box 208114, 266 Whitney Avenue, New Haven, CT 06520-8114, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9353192" target="_blank"〉PubMed〈/a〉
    Keywords: Acylation ; Amino Acid Sequence ; Animals ; Bacteria/enzymology ; Cloning, Molecular ; Electrophoresis, Polyacrylamide Gel ; Euryarchaeota/enzymology/genetics ; Evolution, Molecular ; Genes, Archaeal ; Humans ; Kinetics ; Lysine-tRNA Ligase/*chemistry/*classification/genetics/metabolism ; Methanococcus/*enzymology/genetics ; Molecular Sequence Data ; Phylogeny ; RNA, Transfer, Amino Acyl/biosynthesis ; Sequence Alignment ; Sulfolobus/enzymology
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  • 14
    Publication Date: 1998-12-04
    Description: The M-current regulates the subthreshold electrical excitability of many neurons, determining their firing properties and responsiveness to synaptic input. To date, however, the genes that encode subunits of this important channel have not been identified. The biophysical properties, sensitivity to pharmacological blockade, and expression pattern of the KCNQ2 and KCNQ3 potassium channels were determined. It is concluded that both these subunits contribute to the native M-current.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, H S -- Pan, Z -- Shi, W -- Brown, B S -- Wymore, R S -- Cohen, I S -- Dixon, J E -- McKinnon, D -- New York, N.Y. -- Science. 1998 Dec 4;282(5395):1890-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Cardiology, Department of Physiology and Biophysics, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9836639" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Animals ; Anthracenes/pharmacology ; Brain/metabolism ; Ganglia, Sympathetic/metabolism ; Gene Expression ; Humans ; Indoles/pharmacology ; KCNQ2 Potassium Channel ; KCNQ3 Potassium Channel ; Kinetics ; Neurons/drug effects/physiology ; Oocytes ; Patch-Clamp Techniques ; Potassium/*metabolism ; Potassium Channels/chemistry/drug effects/genetics/*metabolism ; Potassium Channels, Voltage-Gated ; Pyridines/pharmacology ; Rats ; Sympathetic Nervous System/drug effects/physiology ; Tetraethylammonium/pharmacology ; Xenopus
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  • 15
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-11-25
    Description: The human immunodeficiency virus type 1 (HIV-1) shows extensive genetic variation and undergoes rapid evolution. The fidelity of purified HIV-1 reverse transcriptase was measured during DNA polymerization in vitro by means of three different assays. Reverse transcriptase from HIV-1 introduced base-substitution errors in DNA from the bacteriophage phi X174 amber3 at estimated frequencies of 1/2000 to 1/4000. Analyses of misincorporation rates opposite a single template adenine residue showed that HIV-1 reverse transcriptase catalyzed nucleotide mismatches with a specificity of A:C much greater than A:G greater than A:A. The high error rate of HIV-1 reverse transcriptase in vitro translates to approximately five to ten errors per HIV-1 genome per round of replication in vivo. This high error rate suggests that misincorporation by HIV-1 reverse transcriptase is, at least in part, responsible for the hypermutability of the AIDS virus. The specificity of misincorporation may provide a basis for the systematic construction of antiviral nucleosides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Preston, B D -- Poiesz, B J -- Loeb, L A -- CA-07263-03/CA/NCI NIH HHS/ -- N01AI72654/AI/NIAID NIH HHS/ -- R35-CA-39903/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1988 Nov 25;242(4882):1168-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Washington, Seattle 98195.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2460924" target="_blank"〉PubMed〈/a〉
    Keywords: Avian Myeloblastosis Virus/enzymology ; Bacteriophage phi X 174/genetics ; DNA/*biosynthesis ; DNA Polymerase II/metabolism ; DNA, Viral/biosynthesis ; Electrophoresis, Polyacrylamide Gel ; HIV/*enzymology/genetics ; Kinetics ; Moloney murine leukemia virus/enzymology ; Mutation ; Nucleotides/metabolism ; RNA-Directed DNA Polymerase/*metabolism
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  • 16
    Publication Date: 1988-04-22
    Description: BC3H1 myocytes release membrane-bound alkaline phosphatase to the incubation medium upon stimulation with insulin, following a time course that is consistent with the generation of dimyristoylglycerol and the appearance of a putative insulin mediator in the extracellular medium. The use of specific blocking agents shows, however, that alkaline phosphatase release and dimyristoylglycerol production are independent processes and that the blockade of either event inhibits the production of insulin mediator. These experiments suggest a new model of insulin action.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Romero, G -- Luttrell, L -- Rogol, A -- Zeller, K -- Hewlett, E -- Larner, J -- AI 18000/AI/NIAID NIH HHS/ -- AM 14334/AM/NIADDK NIH HHS/ -- AM 22125/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 22;240(4851):509-11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3282305" target="_blank"〉PubMed〈/a〉
    Keywords: Alkaline Phosphatase/metabolism/secretion ; Animals ; Diglycerides/metabolism ; Enzyme Activation/drug effects ; Extracellular Space/enzymology ; Glycolipids/*physiology ; In Vitro Techniques ; Insulin/*pharmacology ; Kinetics ; Membrane Glycoproteins/*physiology ; Phosphatidylinositols/*physiology ; Pyruvate Dehydrogenase Complex/metabolism
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  • 17
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-11-04
    Description: The anticodon has previously been shown to play a role in recognition of certain transfer RNAs by aminoacyl-tRNA synthetases; however, the extent to which this sequence dictates tRNA identity is generally unknown. To investigate the contribution of the anticodon to the identity of Escherichia coli methionine and valine tRNAs, in vitro transcripts of these tRNAs were prepared that contained normal and interchanged anticodon sequences. Transcripts containing wild-type tRNA sequences were excellent substrates for their respective cognate aminoacyl-tRNA synthetases and were effectively discriminated against by a variety of noncognate enzymes. The mutant tRNAs produced by switching the anticodon sequences lost their original tRNA identity and assumed an identity corresponding to the acquired anticodon sequence. These results indicate that the anticodon contains sufficient information to distinguish methionine and valine tRNAs with high fidelity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulman, L H -- Pelka, H -- New York, N.Y. -- Science. 1988 Nov 4;242(4879):765-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Developmental Biology and Cancer, Albert Einstein College of Medicine, Bronx, New York 10461.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3055296" target="_blank"〉PubMed〈/a〉
    Keywords: *Anticodon ; Escherichia coli ; Kinetics ; Methionine-tRNA Ligase/metabolism ; *RNA, Transfer ; RNA, Transfer, Amino Acid-Specific/*physiology ; RNA, Transfer, Met/*physiology ; RNA, Transfer, Val/*physiology ; Substrate Specificity ; *Transfer RNA Aminoacylation ; Valine-tRNA Ligase/metabolism
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  • 18
    Publication Date: 1988-11-25
    Description: A cell-free translation system has been constructed that uses a continuous flow of the feeding buffer [including amino acids, adenosine triphosphate (ATP), and guanosine triphosphate (GTP)] through the reaction mixture and a continuous removal of a polypeptide product. Both prokaryotic (Escherichia coli) and eukaryotic (wheat embryos, Triticum sp.) versions of the system have been tested. In both cases the system has proven active for long times, synthesizing polypeptides at a high constant rate for tens of hours. With the use of MS2 phage RNA or brome mosaic virus RNA 4 as templates, 100 copies of viral coat proteins per RNA were synthesized for 20 hours in the prokaryotic or eukaryotic system, respectively. With synthetic calcitonin messenger RNA, 150 to 300 copies of calcitonin polypeptide were produced per messenger RNA in both types of continuous translation systems for 40 hours.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Spirin, A S -- Baranov, V I -- Ryabova, L A -- Ovodov, S Y -- Alakhov, Y B -- New York, N.Y. -- Science. 1988 Nov 25;242(4882):1162-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Protein Research, Academy of Sciences, Moscow Region, USSR.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3055301" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriophages/genetics ; Calcitonin/biosynthesis/genetics ; Capsid/biosynthesis/genetics ; Electrophoresis ; Escherichia coli/*metabolism ; Kinetics ; Mosaic Viruses/genetics ; *Peptide Biosynthesis ; Plants/*metabolism ; *Protein Biosynthesis ; RNA, Messenger/metabolism ; RNA, Viral/genetics ; Ribosomes/metabolism ; Templates, Genetic ; Triticum
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  • 19
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-01-08
    Description: The Bacillus subtilis ribonuclease P consists of a protein and an RNA. At high ionic strength the reaction is protein-independent; the RNA alone is capable of cleaving precursor transfer RNA, but the turnover is slow. Kinetic analyses show that high salt concentrations facilitate substrate binding in the absence of the protein, probably by decreasing the repulsion between the polyanionic enzyme and substrate RNAs, and also slow product release and enzyme turnover. It is proposed that the ribonuclease P protein, which is small and basic, provides a local pool of counter-ions that facilitates substrate binding without interfering with rapid product release.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reich, C -- Olsen, G J -- Pace, B -- Pace, N R -- GM34527/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jan 8;239(4836):178-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Indiana University, Bloomington 47405.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3122322" target="_blank"〉PubMed〈/a〉
    Keywords: Bacillus subtilis/*enzymology ; Endoribonucleases/*physiology ; Kinetics ; Nucleic Acid Precursors/metabolism ; RNA, Transfer/metabolism ; Ribonuclease P ; Ribonucleoproteins/*physiology ; Structure-Activity Relationship
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  • 20
    Publication Date: 1988-12-16
    Description: The fidelity of protein biosynthesis in any cell rests on the accuracy of aminoacylation of tRNA. The exquisite specificity of this reaction is critically dependent on the correct recognition of tRNA by aminoacyl-tRNA synthetases. It is shown here that the relative concentrations of a tRNA and its cognate aminoacyl-tRNA synthetase are normally well balanced and crucial for maintenance of accurate aminoacylation. When Escherichia coli Gln-tRNA synthetase is overproduced in vivo, it incorrectly acylates the supF amber suppressor tRNA(Tyr) with Gln. This effect is abolished when the intracellular concentration of the cognate tRNA(Gln2) is also elevate. These data indicate that the presence of aminoacyl-tRNA synthetase and the cognate tRNAs in complexed form, which requires the proper balance of the two macromolecules, is critical in maintaining the fidelity of protein biosynthesis. Thus, limits exist on the relative levels of tRNAs and aminoacyl-tRNA synthetases within a cell.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Swanson, R -- Hoben, P -- Sumner-Smith, M -- Uemura, H -- Watson, L -- Soll, D -- New York, N.Y. -- Science. 1988 Dec 16;242(4885):1548-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3144042" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acyl-tRNA Synthetases/genetics/*metabolism ; Escherichia coli/enzymology/*genetics ; Kinetics ; Plasmids ; RNA, Transfer, Amino Acid-Specific/*metabolism ; RNA, Transfer, Gln/*metabolism ; beta-Galactosidase/genetics/metabolism
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  • 21
    Publication Date: 1988-12-09
    Description: Potassium channels in neurons are linked by guanine nucleotide binding (G) proteins to numerous neurotransmitter receptors. The ability of Go, the predominant G protein in the brain, to stimulate potassium channels was tested in cell-free membrane patches of hippocampal pyramidal neurons. Four distinct types of potassium channels, which were otherwise quiescent, were activated by both isolated brain G0 and recombinant Go alpha. Hence brain Go can couple diverse brain potassium channels to neurotransmitter receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉VanDongen, A M -- Codina, J -- Olate, J -- Mattera, R -- Joho, R -- Birnbaumer, L -- Brown, A M -- DK-19318/DK/NIDDK NIH HHS/ -- HL-31154/HL/NHLBI NIH HHS/ -- HL-37044/HL/NHLBI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Dec 9;242(4884):1433-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3144040" target="_blank"〉PubMed〈/a〉
    Keywords: Adenylyl Imidodiphosphate/pharmacology ; Animals ; Cattle ; Electric Conductivity ; GTP-Binding Proteins/*pharmacology ; Hippocampus/*physiology ; In Vitro Techniques ; Kinetics ; Macromolecular Substances ; Membrane Potentials/drug effects ; Potassium Channels/drug effects/*physiology ; Pyramidal Tracts/physiology ; Rats ; Recombinant Proteins/*pharmacology
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  • 22
    Publication Date: 1988-06-10
    Description: Proteins undergo a series of nonenzymatic reactions with glucose over time to form advanced glycosylation end products (AGEs). Macrophages have a receptor that recognizes the AGE moiety and mediates the uptake and degradation of AGE proteins. This removal process is associated with the production and secretion of cachectin (tumor necrosis factor) and interleukin-1, two cytokines with diverse and seemingly paradoxical biological activities. The localized release and action of these cytokines could account for the coordinated removal and replacement of senescent extracellular matrix components in normal tissue homeostasis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vlassara, H -- Brownlee, M -- Manogue, K R -- Dinarello, C A -- Pasagian, A -- R01-AI15674/AI/NIAID NIH HHS/ -- R01-AM19655/AM/NIADDK NIH HHS/ -- R01-AM33861/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 10;240(4858):1546-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Medical Biochemistry, Rockefeller University, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3259727" target="_blank"〉PubMed〈/a〉
    Keywords: Glycosylation ; Humans ; Interleukin-1/*biosynthesis/genetics ; Kinetics ; Membrane Glycoproteins/*physiology ; Monocytes/*metabolism ; Protein Biosynthesis ; RNA, Messenger/genetics ; Tumor Necrosis Factor-alpha/*biosynthesis/genetics
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  • 23
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-06-17
    Description: Biochemical and electrophysiological studies suggest that adenosine 3',5'-monophosphate (cAMP)-dependent phosphorylation of the nicotinic acetylcholine receptor channel is functionally significant because it modifies the receptor's rate of desensitization to acetylcholine. In studies that support this conclusion researchers have used forskolin to stimulate cAMP-dependent phosphorylation in intact muscle. It is now shown that although forskolin facilitated desensitization in voltage-clamped rat muscle, this effect was not correlated with the abilities of forskolin and forskolin analogs to activate adenylate cyclase or phosphorylate the receptor. Furthermore, elevation of intracellular cAMP or addition of the catalytic subunit of A-kinase failed to alter desensitization. Therefore, in intact skeletal muscle, cAMP-dependent phosphorylation does not modulate desensitization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wagoner, P K -- Pallotta, B S -- GM32211/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 17;240(4859):1655-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Pharmacology, Glaxo Research Laboratories, Chapel Hill, NC 27599.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2454507" target="_blank"〉PubMed〈/a〉
    Keywords: 1-Methyl-3-isobutylxanthine/pharmacology ; Acetylcholine/pharmacology ; Adenylyl Cyclases/metabolism ; Animals ; Bucladesine/pharmacology ; Colforsin/*pharmacology ; Cyclic AMP/analogs & derivatives/*pharmacology ; Electric Conductivity ; Enzyme Activation/drug effects ; Kinetics ; Muscles/*metabolism ; Phosphorylation ; Rats ; Receptors, Cholinergic/drug effects/*physiology ; Torpedo/metabolism
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  • 24
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-10-07
    Description: The enzymes adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (protein kinase A) and protein kinase C regulate the activity of a diverse group of cellular proteins including membrane ion channel proteins. When protein kinase A was stimulated in cardiac ventricular myocytes with the membrane-soluble cAMP analog 8-chlorphenylthio cAMP (8-CPT cAMP), the amplitude of the delayed-rectifier potassium current (IK) doubled when recorded at 32 degrees C but was not affected at 22 degrees C. In contrast, modulation of the calcium current (ICa) by 8-CPT cAMP was independent of temperature with similar increases in ICa occurring at both temperatures. Stimulation of protein kinase C by phorbol 12,13-dibutyrate also enhanced IK in a temperature-dependent manner but failed to increase ICa at either temperature. Thus, cardiac delayed-rectifier potassium but not calcium channels are regulated by two distinct protein kinases in a similar temperature-dependent fashion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Walsh, K B -- Kass, R S -- New York, N.Y. -- Science. 1988 Oct 7;242(4875):67-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Rochester, School of Medicine and Dentistry, NY 14642.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2845575" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cyclic AMP/*analogs & derivatives/pharmacology ; Guinea Pigs ; Heart/*physiology ; Homeostasis ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Potassium Channels/*physiology ; Protein Kinase C/*metabolism ; Protein Kinases/*metabolism ; Thermodynamics ; Thionucleotides/*pharmacology ; Ventricular Function
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  • 25
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-05
    Description: Tumor promoters may bring about events that lead to neoplastic transformation by inducing specific promotion-relevant effector genes. Functional activation of the transacting transcription factor AP-1 by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) may play an essential role in this process. Clonal genetic variants of mouse epidermal JB6 cells that are genetically susceptible (P+) or resistant (P-) to promotion of transformation by TPA were transfected with 3XTRE-CAT, a construct that has AP-1 cis-enhancer sequences attached to a reporter gene encoding chloramphenicol acetyltransferase (CAT). Transfected JB6 P+, but not P- variants, showed TPA-inducible CAT synthesis. Epidermal growth factor, another transformation promoter in JB6 cells, also caused P+ specific induction of CAT gene expression. These results demonstrate an association between induced AP-1 function and sensitivity to promotion of neoplastic transformation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernstein, L R -- Colburn, N H -- New York, N.Y. -- Science. 1989 May 5;244(4904):566-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Johns Hopkins University, Department of Biology, Baltimore, MD 21218.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2541502" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; *Cell Transformation, Neoplastic ; Chloramphenicol O-Acetyltransferase/genetics ; Cloning, Molecular ; DNA-Binding Proteins/genetics/*physiology ; Epidermal Growth Factor/pharmacology ; Epidermis ; Gene Expression Regulation ; Genetic Variation ; Kinetics ; Mice ; Nucleic Acid Hybridization ; Plasmids ; Promoter Regions, Genetic ; Proto-Oncogene Proteins ; Proto-Oncogene Proteins c-jun ; Simplexvirus/genetics ; Tetradecanoylphorbol Acetate/*pharmacology ; Transcription Factors/genetics/*physiology ; Transfection
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  • 26
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-04-28
    Description: The specific hydrolysis of unactivated esters bearing an R or S enantiomeric alcohol has been achieved by two separate classes of catalytic antibodies induced to bind either the R or S substrates. The antibodies exhibit rate accelerations (10(3) to 10(5] above background hydrolysis that, coupled with their antipodal specificity, provide a novel set of reagents for use in synthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Janda, K D -- Benkovic, S J -- Lerner, R A -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):437-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2717936" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antibodies, Monoclonal/immunology ; Antibody Specificity ; Antigens/immunology ; Benzyl Alcohols/metabolism ; *Catalysis ; Esters/metabolism ; Haptens ; Hemocyanin/immunology ; Hydrolysis ; Immunization ; Kinetics ; Lipase/*metabolism ; Mice ; Mice, Inbred A ; Molecular Structure ; Organophosphonates/immunology ; Stereoisomerism ; Substrate Specificity
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  • 27
    Publication Date: 1989-03-10
    Description: Antisense RNA-mediated inhibition of gene expression was used to investigate the biological function of the c-raf-1 gene in a radiation-resistant human squamous carcinoma cell line, SQ-20B. S1 nuclease protection assays revealed that transfection of full-length raf complementary DNA in the antisense orientation (AS) leads to a specific reduction (greater than tenfold) of steady-state levels of the endogenous c-raf-1 sense (S) transcript in SQ-20B cells. In nude mice, the malignant potential of SQ-20B cells transfected with raf (S) was significantly increased relative to that of SQ-20B cells transfected with raf (AS). SQ-20B cells containing transfected raf (S) maintained a radiation-resistant phenotype as compared to those cells harboring the AS version, which appeared to have enhanced radiation sensitivity. These data indicate that the reduced expression of endogenous c-raf-1 is sufficient to modulate the tumorigenicity and the radiation-resistant phenotype of SQ-20B cells, thus implicating c-raf-1 in a pathway important to the genesis of this type of cancer.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kasid, U -- Pfeifer, A -- Brennan, T -- Beckett, M -- Weichselbaum, R R -- Dritschilo, A -- Mark, G E -- New York, N.Y. -- Science. 1989 Mar 10;243(4896):1354-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Radiation Medicine, Vincent T. Lombardi Comprehensive Cancer Research Center, Georgetown University Medical Center, Washington 20007.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2466340" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blotting, Southern ; Carcinoma, Squamous Cell/*genetics ; Cell Line ; Cell Survival/*radiation effects ; Clone Cells ; Dose-Response Relationship, Radiation ; *Gene Expression Regulation ; Humans ; Kinetics ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Nucleic Acid Hybridization ; *Proto-Oncogenes ; RNA/*genetics ; RNA, Antisense ; RNA, Messenger/*antagonists & inhibitors ; Transcription, Genetic ; Transfection ; Transplantation, Heterologous ; Tumor Cells, Cultured/*radiation effects
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  • 28
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-09
    Description: Two types of potassium-selective channels activated by intracellular arachidonic acid or phosphatidylcholine have been found in neonatal rat atrial cells. In inside-out patches, arachidonic acid and phosphatidylcholine each opened outwardly rectifying potassium-selective channels with conductances of 160 picosiemens (IK.AA) and 68 picosiemens (IK.PC), respectively. These potassium channels were not sensitive to internally applied adenosine triphosphate (ATP), magnesium, or calcium. Lowering the intracellular pH from 7.2 to 6.8 or 6.4 reversibly increased IK.AA channel activity three- or tenfold, respectively. A number of fatty acid derivatives were tested for their ability to activate IK.AA. These potassium-selective channels may help explain the increase in potassium conductance observed in ischemic cells and raise the possibility that fatty acid derivatives act as second messengers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, D -- Clapham, D E -- HL 34873/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1174-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Mayo Foundation, Rochester, MN 55905.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727703" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Animals, Newborn ; Arachidonic Acids/*pharmacology ; Atrial Function ; Heart/*physiology ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Phosphatidylcholines/*pharmacology ; Potassium Channels/drug effects/*physiology ; Rats
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  • 29
    Publication Date: 1989-09-15
    Description: The neutrophil Mac-1 and gp100MEL-14 adhesion proteins are involved in neutrophil extravasation during inflammation. Both the expression and activity of Mac-1 are greatly increased after neutrophil activation. In contrast, neutrophils shed gp100MEL-14 from the cell surface within 4 minutes after activation with chemotactic factors or phorbol esters, releasing a 96-kilodalton fragment of the antigen into the supernatant. Immunohistology showed that gp100MEL-14 was downregulated on neutrophils that had extravasated into inflamed tissue. The gp100MEL-14 adhesion protein may participate in the binding of unactivated neutrophils to the endothelium; rapid shedding of gp100MEL-14 may prevent extravasation into and damage of normal tissues by activated neutrophils.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kishimoto, T K -- Jutila, M A -- Berg, E L -- Butcher, E C -- AI 19957/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 15;245(4923):1238-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Stanford University, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2551036" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, Differentiation/*immunology ; Antigens, Surface/*immunology ; Bone Marrow Cells ; Cell Adhesion ; Cell Adhesion Molecules ; Chemotactic Factors/*physiology ; Complement C5/physiology ; Complement C5a ; Fluorescent Antibody Technique ; Interleukin-1/physiology ; Interleukin-8 ; Kinetics ; Leukotriene B4/physiology ; Lipopolysaccharides/physiology ; Lymphocyte Activation ; Macrophage Activation ; Macrophage-1 Antigen ; Mice ; Mice, Inbred BALB C ; Neutrophils/cytology/*immunology ; Tetradecanoylphorbol Acetate ; Tumor Necrosis Factor-alpha/physiology
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  • 30
    Publication Date: 1989-04-07
    Description: Protein engineering and x-ray crystallography have been used to study the role of a surface loop that is present in pancreatic phospholipases but is absent in snake venom phospholipases. Removal of residues 62 to 66 from porcine pancreatic phospholipase A2 does not change the binding constant for micelles significantly, but it improves catalytic activity up to 16 times on micellar (zwitterionic) lecithin substrates. In contrast, the decrease in activity on negatively charged substrates is greater than fourfold. A crystallographic study of the mutant enzyme shows that the region of the deletion has a well-defined structure that differs from the structure of the wild-type enzyme. No structural changes in the active site of the enzyme were detected.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kuipers, O P -- Thunnissen, M M -- de Geus, P -- Dijkstra, B W -- Drenth, J -- Verheij, H M -- de Haas, G H -- New York, N.Y. -- Science. 1989 Apr 7;244(4900):82-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Utrecht, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2704992" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Crystallography ; Enzyme Activation ; Kinetics ; Molecular Sequence Data ; Mutation ; Pancreas/enzymology ; Phospholipases/*metabolism ; Phospholipases A/genetics/*metabolism/physiology ; Phospholipases A2 ; *Protein Conformation ; Snake Venoms/analysis ; Structure-Activity Relationship ; Swine
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  • 31
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-08-04
    Description: The origin of allostery is an unanswered question in the evolution of complex regulatory proteins. Anabolic ornithine transcarbamoylase, a trimer of identical subunits, is not an allosteric enzyme per se. However, when the active-site residue arginine-106 of the Escherichia coli enzyme is replaced with a glycine through site-directed mutagenesis, the resultant mutant enzyme manifests substrate cooperativity that is absent in the wild-type enzyme. Both homotropic and heterotropic interactions occur in the mutant enzyme. The initial velocity saturation curves of the substrates, carbamoyl phosphate and L-ornithine, conform to the Hill equation. The observed cooperativity depends on substrate but not enzyme concentration. The finding underscores the possibility that a single mutation of the enzyme in the cell could turn transcarbamoylation into a regulatory junction in the biosynthesis of L-arginine and urea.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kuo, L C -- Zambidis, I -- Caron, C -- DK01721/DK/NIDDK NIH HHS/ -- DK38089/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Aug 4;245(4917):522-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Metcalf Center for Science and Engineering, Boston University, MA 02215.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2667139" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Binding Sites ; Carbamyl Phosphate/metabolism ; Escherichia coli/*enzymology ; Glycine ; Kinetics ; Macromolecular Substances ; *Mutation ; Ornithine/metabolism ; Ornithine Carbamoyltransferase/*genetics/metabolism ; Structure-Activity Relationship ; Zinc/pharmacology
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  • 32
    Publication Date: 1989-07-07
    Description: Basic fibroblast growth factor (bFGF) participates in many processes including early developmental events, angiogenesis, wound healing, and maintenance of neuronal cell viability. A 130-kilodalton protein was isolated on the basis of its ability to specifically bind to bFGF. A complementary DNA clone was isolated with an oligonucleotide probe corresponding to determined amino acid sequences of tryptic peptide fragments of the purified protein. The putative bFGF receptor encoded by this complementary DNA is a transmembrane protein that contains three extracellular immunoglobulin-like domains, an unusual acidic region, and an intracellular tyrosine kinase domain. These domains are arranged in a pattern that is different from that of any growth factor receptor described.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, P L -- Johnson, D E -- Cousens, L S -- Fried, V A -- Williams, L T -- CA 21765/CA/NCI NIH HHS/ -- R01 HL32898/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jul 7;245(4913):57-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Medicine, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2544996" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cells, Cultured ; Chick Embryo ; *Cloning, Molecular ; DNA/*genetics ; Fibroblast Growth Factors/*genetics ; Kinetics ; Mice ; Molecular Sequence Data ; Peptide Fragments/analysis ; Receptors, Cell Surface/*genetics/metabolism ; Receptors, Fibroblast Growth Factor ; Recombinant Proteins/metabolism
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  • 33
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-17
    Description: Rana esculenta tropomyosin assembles in vivo into a coiled-coil alpha helix from two different subunits, alpha and beta, which are present in about equal concentrations. Although the native composition is alpha beta, a mixture of equal amounts of alpha alpha and beta beta is produced by refolding dissociated alpha and beta at low temperature in vitro. Refolding kinetics showed that alpha alpha formed first and was relatively stable with regard to chain exchange below approximately 20 degrees C. Equilibration of the homodimer mixture at 30 degrees and 34 degrees C for long times, however, resulted in the formation of the native alpha beta molecule by chain exchange. Biosynthesis of alpha beta from separate alpha and beta genes is, therefore, favored thermodynamically over the formation of homodimers, and biological factors need not be invoked to explain the preferred native alpha beta composition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lehrer, S S -- Qian, Y D -- Hvidt, S -- HL22461/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Nov 17;246(4932):926-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Muscle Research, Boston Biomedical Research Institute, MA 02114.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814515" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Kinetics ; Macromolecular Substances ; Muscle, Smooth/metabolism ; Muscles/metabolism ; Myocardium/metabolism ; Protein Conformation ; Protein Denaturation ; Protein Processing, Post-Translational ; Rana esculenta ; Thermodynamics ; Tropomyosin/genetics/*metabolism
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  • 34
    Publication Date: 1989-01-13
    Description: An important question in protein folding is whether the natural amino and carboxyl termini and the given order of secondary structure segments are critical to the stability and to the folding pathway of proteins. Here it is shown that two circularly permuted versions of the gene of a single-domain beta alpha barrel enzyme can be expressed in Escherichia coli. The variants are enzymically active and are practically indistinguishable from the original enzyme by several structural and spectroscopic criteria, despite the creation of new termini and the cleavage of a surface loop. This novel genetic approach should be useful for protein folding studies both in vitro and in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luger, K -- Hommel, U -- Herold, M -- Hofsteenge, J -- Kirschner, K -- New York, N.Y. -- Science. 1989 Jan 13;243(4888):206-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Abteilung Biophysikalische Chemie, Universitat Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2643160" target="_blank"〉PubMed〈/a〉
    Keywords: *Aldose-Ketose Isomerases ; Amino Acid Sequence ; Base Sequence ; Carbohydrate Epimerases/*genetics/metabolism ; Circular Dichroism ; *Cloning, Molecular ; Enzyme Stability ; Escherichia coli/*enzymology/genetics ; *Genes ; Genetic Variation ; Kinetics ; Molecular Sequence Data ; *Protein Conformation ; Spectrometry, Fluorescence ; Spectrophotometry, Ultraviolet
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  • 35
    Publication Date: 1998-05-02
    Description: Members of the kinesin superfamily of motor proteins are essential for mitotic and meiotic spindle organization, chromosome segregation, organelle and vesicle transport, and many other processes that require microtubule-based transport. A compound, adociasulfate-2, was isolated from a marine sponge, Haliclona (also known as Adocia) species, that inhibited kinesin activity by targeting its motor domain and mimicking the activity of the microtubule. Thus, the kinesin-microtubule interaction site could be a useful target for small molecule modulators, and adociasulfate-2 should serve as an archetype for specific inhibitors of kinesin functions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sakowicz, R -- Berdelis, M S -- Ray, K -- Blackburn, C L -- Hopmann, C -- Faulkner, D J -- Goldstein, L S -- New York, N.Y. -- Science. 1998 Apr 10;280(5361):292-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Division of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0683, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9535660" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Diphosphate/metabolism ; Adenosine Triphosphatases/antagonists & inhibitors ; Adenosine Triphosphate/metabolism ; Animals ; Binding Sites ; Cell Division/drug effects ; Drosophila/embryology ; Enzyme Inhibitors/chemistry/*isolation & purification/*pharmacology ; HeLa Cells ; Humans ; Kinesin/*antagonists & inhibitors/metabolism ; Kinetics ; Microtubules/*metabolism ; Mitosis/drug effects ; Porifera/*chemistry ; Sulfuric Acid Esters/chemistry/*isolation & purification/*pharmacology
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  • 36
    Publication Date: 1998-08-26
    Description: Nitrogen-fixing bacteroids in legume root nodules are surrounded by the plant-derived peribacteroid membrane, which controls nutrient transfer between the symbionts. A nodule complementary DNA (GmSAT1) encoding an ammonium transporter has been isolated from soybean. GmSAT1 is preferentially transcribed in nodules and immunoblotting indicates that GmSAT1 is located on the peribacteroid membrane. [14C]methylammonium uptake and patch-clamp analysis of yeast expressing GmSAT1 demonstrated that it shares properties with a soybean peribacteroid membrane NH4〈SUP ARRANGE="STAGGER"〉+ channel described elsewhere. GmSAT1 is likely to be involved in the transfer of fixed nitrogen from the bacteroid to the host.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, B N -- Finnegan, P M -- Tyerman, S D -- Whitehead, L F -- Bergersen, F J -- Day, D A -- Udvardi, M K -- New York, N.Y. -- Science. 1998 Aug 21;281(5380):1202-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biochemistry and Molecular Biology, The Australian National University, Canberra ACT 0200, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9712587" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Biological Transport ; Carrier Proteins/chemistry/*genetics/*metabolism/*secretion ; *Cation Transport Proteins ; Cell Membrane/metabolism ; DNA, Complementary ; Ion Channels/metabolism ; Kinetics ; Methylamines/metabolism ; Molecular Sequence Data ; Organelles/metabolism ; Patch-Clamp Techniques ; Plant Roots/genetics/metabolism/microbiology ; Potassium/metabolism ; Quaternary Ammonium Compounds/*metabolism ; Saccharomyces cerevisiae/genetics/metabolism ; *Soybean Proteins ; Soybeans/chemistry/*genetics/metabolism/microbiology ; Spheroplasts/metabolism ; Symbiosis ; Transformation, Genetic
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  • 37
    Publication Date: 1998-07-04
    Description: Actin filament assembly at the cell surface of the pathogenic bacterium Listeria monocytogenes requires the bacterial ActA surface protein and the host cell Arp2/3 complex. Purified Arp2/3 complex accelerated the nucleation of actin polymerization in vitro, but pure ActA had no effect. However, when combined, the Arp2/3 complex and ActA synergistically stimulated the nucleation of actin filaments. This mechanism of activating the host Arp2/3 complex at the L. monocytogenes surface may be similar to the strategy used by cells to control Arp2/3 complex activity and hence the spatial and temporal distribution of actin polymerization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Welch, M D -- Rosenblatt, J -- Skoble, J -- Portnoy, D A -- Mitchison, T J -- AI26919/AI/NIAID NIH HHS/ -- GM48027/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Jul 3;281(5373):105-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9651243" target="_blank"〉PubMed〈/a〉
    Keywords: Actin-Related Protein 2 ; Actin-Related Protein 3 ; Actins/chemistry/*metabolism/ultrastructure ; Bacterial Proteins/chemistry/*metabolism ; Biopolymers ; Cell Membrane/metabolism ; Cytochalasin D/pharmacology ; *Cytoskeletal Proteins ; Humans ; Kinetics ; Listeria monocytogenes/*metabolism ; Membrane Proteins/chemistry/*metabolism ; Microscopy, Electron
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  • 38
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-05-09
    Description: Fluorescence in situ hybridization (FISH) and digital imaging microscopy were modified to allow detection of single RNA molecules. Oligodeoxynucleotide probes were synthesized with five fluorochromes per molecule, and the light emitted by a single probe was calibrated. Points of light in exhaustively deconvolved images of hybridized cells gave fluorescent intensities and distances between probes consistent with single messenger RNA molecules. Analysis of beta-actin transcription sites after serum induction revealed synchronous and cyclical transcription from single genes. The rates of transcription initiation and termination and messenger RNA processing could be determined by positioning probes along the transcription unit. This approach extends the power of FISH to yield quantitative molecular information on a single cell.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Femino, A M -- Fay, F S -- Fogarty, K -- Singer, R H -- GM 54887/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Apr 24;280(5363):585-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Anatomy and Structural Biology and Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9554849" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/genetics ; Animals ; Cell Line ; Fluorescein-5-isothiocyanate ; *In Situ Hybridization, Fluorescence ; Kinetics ; Oligonucleotide Probes ; RNA Processing, Post-Transcriptional ; RNA, Messenger/*analysis/*genetics/metabolism ; Rats ; *Transcription, Genetic
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  • 39
    Publication Date: 1998-10-02
    Description: To better understand the dynamics of hepatitis C virus and the antiviral effect of interferon-alpha-2b (IFN), viral decline in 23 patients during therapy was analyzed with a mathematical model. The analysis indicates that the major initial effect of IFN is to block virion production or release, with blocking efficacies of 81, 95, and 96% for daily doses of 5, 10, and 15 million international units, respectively. The estimated virion half-life (t1/2) was, on average, 2.7 hours, with pretreatment production and clearance of 10(12) virions per day. The estimated infected cell death rate exhibited large interpatient variation (corresponding t1/2 = 1.7 to 70 days), was inversely correlated with baseline viral load, and was positively correlated with alanine aminotransferase levels. Fast death rates were predictive of virus being undetectable by polymerase chain reaction at 3 months. These findings show that infection with hepatitis C virus is highly dynamic and that early monitoring of viral load can help guide therapy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Neumann, A U -- Lam, N P -- Dahari, H -- Gretch, D R -- Wiley, T E -- Layden, T J -- Perelson, A S -- A1/DK41320-2/DK/NIDDK NIH HHS/ -- A139049-2/PHS HHS/ -- RR06555/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1998 Oct 2;282(5386):103-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9756471" target="_blank"〉PubMed〈/a〉
    Keywords: Alanine Transaminase/blood ; Antiviral Agents/administration & dosage/*therapeutic use ; Cell Death ; Dose-Response Relationship, Drug ; Half-Life ; Hepacivirus/*physiology ; Hepatitis C/immunology/*therapy/*virology ; Humans ; Interferon-alpha/administration & dosage/*therapeutic use ; Kinetics ; Models, Biological ; RNA, Viral/blood ; Recombinant Proteins ; Regression Analysis ; Viral Load ; Viremia/virology ; Virion/physiology ; Virus Replication
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  • 40
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-05-23
    Description: Xenopus oocytes convert a continuously variable stimulus, the concentration of the maturation-inducing hormone progesterone, into an all-or-none biological response-oocyte maturation. Here evidence is presented that the all-or-none character of the response is generated by the mitogen-activated protein kinase (MAPK) cascade. Analysis of individual oocytes showed that the response of MAPK to progesterone or Mos was equivalent to that of a cooperative enzyme with a Hill coefficient of at least 35, more than 10 times the Hill coefficient for the binding of oxygen to hemoglobin. The response can be accounted for by the intrinsic ultrasensitivity of the oocyte's MAPK cascade and a positive feedback loop in which the cascade is embedded. These findings provide a biochemical rationale for the all-or-none character of this cell fate switch.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ferrell, J E Jr -- Machleder, E M -- CA09302/CA/NCI NIH HHS/ -- GM56383/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 May 8;280(5365):895-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, CA 94305-5332, USA. ferrell@cmgm.stanford.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9572732" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Carrier Proteins/pharmacology ; Cell Cycle ; Cycloheximide/pharmacology ; Enzyme Activation ; Feedback ; Kinetics ; Maltose-Binding Proteins ; Mitogen-Activated Protein Kinase 1/*metabolism ; Oocytes/*cytology/drug effects/enzymology/*metabolism ; Phosphorylation ; Progesterone/*pharmacology ; Protein Synthesis Inhibitors/pharmacology ; Proto-Oncogene Proteins c-mos/*pharmacology ; Recombinant Fusion Proteins/pharmacology
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  • 41
    Publication Date: 1998-03-21
    Description: Studies of lymphocyte turnover in animal models have implications for understanding the mechanism of cell killing and the extent of lymphocyte regeneration in human immunodeficiency virus infection. Quantitative analyses of the sequential changes in bromodeoxyuridine labeling of CD4 and CD8 T lymphocytes not only revealed the normal proliferation and death rates of these cell populations in uninfected macaques, but also showed a substantial increase in these rates associated with simian immunodeficiency virus (SIV) infection. Faster labeling and delabeling in memory and naive T lymphocyte subpopulations as well as in NK (natural killer) and B cells were also observed in infected macaques, suggesting a state of generalized activation induced by SIV.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mohri, H -- Bonhoeffer, S -- Monard, S -- Perelson, A S -- Ho, D D -- AI40387/AI/NIAID NIH HHS/ -- AI41534/AI/NIAID NIH HHS/ -- AI45128/AI/NIAID NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1998 Feb 20;279(5354):1223-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Aaron Diamond AIDS Research Center, The Rockefeller University, 455 First Avenue, New York, NY 10016, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9469816" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bromodeoxyuridine/metabolism ; CD4 Lymphocyte Count ; CD4-Positive T-Lymphocytes/*immunology/pathology ; CD8-Positive T-Lymphocytes/*immunology/pathology ; Cell Death ; Cell Division ; Humans ; Kinetics ; Lymphocyte Activation ; Lymphocyte Count ; Macaca mulatta ; Mathematics ; Models, Biological ; Regression Analysis ; Simian Acquired Immunodeficiency Syndrome/*immunology/virology ; Simian Immunodeficiency Virus/physiology ; T-Lymphocyte Subsets/*immunology/pathology ; Viral Load
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  • 42
    Publication Date: 1997-07-11
    Description: Small structural perturbations in the enzyme isocitrate dehydrogenase (IDH) were made in order to evaluate the contribution of precise substrate alignment to the catalytic power of an enzyme. The reaction trajectory of IDH was modified (i) after the adenine moiety of nicotinamide adenine dinucleotide phosphate was changed to hypoxanthine (the 6-amino was changed to 6-hydroxyl), and (ii) by replacing Mg2+, which has six coordinating ligands, with Ca2+, which has eight coordinating ligands. Both changes make large (10(-3) to 10(-5)) changes in the reaction velocity but only small changes in the orientation of the substrates (both distance and angle) as revealed by cryocrystallographic trapping of active IDH complexes. The results provide evidence that orbital overlap produced by optimal orientation of reacting orbitals plays a major quantitative role in the catalytic power of enzymes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mesecar, A D -- Stoddard, B L -- Koshland, D E Jr -- GM49857/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jul 11;277(5323):202-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, Stanley Hall, University of California, Berkeley, CA 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9211842" target="_blank"〉PubMed〈/a〉
    Keywords: Cadmium/metabolism ; Calcium/metabolism ; Catalysis ; Chemistry, Physical ; Crystallography, X-Ray ; Hydrogen Bonding ; Isocitrate Dehydrogenase/*chemistry/*metabolism ; Kinetics ; Ligands ; Magnesium/metabolism ; Models, Molecular ; Mutagenesis, Site-Directed ; NAD/analogs & derivatives/metabolism ; NADP/metabolism ; Physicochemical Phenomena ; *Protein Conformation
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  • 43
    Publication Date: 1997-01-03
    Description: The controversial question of how thiamine diphosphate, the biologically active form of vitamin B1, is activated in different enzymes has been addressed. Activation of the coenzyme was studied by measuring thermodynamics and kinetics of deprotonation at the carbon in the 2-position (C2) of thiamine diphosphate in the enzymes pyruvate decarboxylase and transketolase by use of nuclear magnetic resonance spectroscopy, proton/deuterium exchange, coenzyme analogs, and site-specific mutant enzymes. Interaction of a glutamate with the nitrogen in the 1'-position in the pyrimidine ring activated the 4'-amino group to act as an efficient proton acceptor for the C2 proton. The protein component accelerated the deprotonation of the C2 atom by several orders of magnitude, beyond the rate of the overall enzyme reaction. Therefore, the earlier proposed concerted mechanism or stabilization of a C2 carbanion can be excluded.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kern, D -- Kern, G -- Neef, H -- Tittmann, K -- Killenberg-Jabs, M -- Wikner, C -- Schneider, G -- Hubner, G -- New York, N.Y. -- Science. 1997 Jan 3;275(5296):67-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Biochemie, Martin-Luther Universitat Halle-Wittenberg, Kurt-Mothes-Strasse 3, D-06120 Halle, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8974393" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Binding Sites ; Catalysis ; Deuterium/metabolism ; Enzyme Activation ; Glutamic Acid/metabolism ; Hydrogen-Ion Concentration ; Kinetics ; Magnetic Resonance Spectroscopy ; Mutagenesis, Site-Directed ; Protons ; Pyruvate Decarboxylase/chemistry/*metabolism ; Pyruvates/metabolism ; Thermodynamics ; Thiamine Pyrophosphate/chemistry/*metabolism ; Transketolase/chemistry/*metabolism
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  • 44
    Publication Date: 1998-07-31
    Description: In experiments modeling volcanic or hydrothermal settings amino acids were converted into their peptides by use of coprecipitated (Ni,Fe)S and CO in conjunction with H2S (or CH3SH) as a catalyst and condensation agent at 100 degreesC and pH 7 to 10 under anaerobic, aqueous conditions. These results demonstrate that amino acids can be activated under geochemically relevant conditions. They support a thermophilic origin of life and an early appearance of peptides in the evolution of a primordial metabolism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huber, C -- Wachtershauser, G -- New York, N.Y. -- Science. 1998 Jul 31;281(5377):670-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department for Organic Chemistry and Biochemistry, Technische Universitat Munchen, Lichtenbergstrasse 4, D-85747 Garching, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9685253" target="_blank"〉PubMed〈/a〉
    Keywords: Acetic Acid/chemical synthesis ; Amino Acids/chemistry ; Aminoacylation ; Anaerobiosis ; Carbon Monoxide/*chemistry ; Catalysis ; Dipeptides/chemical synthesis ; Ferrous Compounds/*chemistry ; Hot Temperature ; Hydrogen Sulfide/chemistry ; Hydrogen-Ion Concentration ; Kinetics ; Nickel/*chemistry ; *Origin of Life ; *Peptide Biosynthesis ; Sulfhydryl Compounds/chemistry ; Thermodynamics
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  • 45
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-03
    Description: An important control point in gene expression is at the level of messenger RNA (mRNA) stability. The mRNAs of certain regulatory cellular proteins such as oncogenes, cytokines, lymphokines, and transcriptional activators are extremely labile. These messages share a common AUUUA pentamer in their 3' untranslated region, which confers cytoplasmic instability. A cytosolic protein was identified that binds specifically to RNA molecules containing four reiterations of the AUUUA structural element. This protein consists of three subunits and binds rapidly to AUUUA-containing RNA. Such protein-RNA complexes are resistant to the actions of denaturing and reducing agents, demonstrating very stable binding. The time course, stability, and specificity of the protein-AUUUA interaction suggests the possibility that the formation of this complex may target susceptible mRNA for rapid cytoplasmic degradation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malter, J S -- CA01427-01/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1989 Nov 3;246(4930):664-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Tulane University School of Medicine, New Orleans, LA 70112.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814487" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding, Competitive ; Carrier Proteins/isolation & purification/*metabolism ; Cell Line ; Humans ; Kinetics ; Macromolecular Substances ; Molecular Weight ; *Nucleocytoplasmic Transport Proteins ; RNA, Messenger/*metabolism ; *RNA-Binding Proteins ; Ribonuclease, Pancreatic
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  • 46
    Publication Date: 1989-06-09
    Description: Arachidonic acid, as well as fatty acids that are not substrates for cyclooxygenase and lipoxygenase enzymes, activated a specific type of potassium channel in freshly dissociated smooth muscle cells. Activation occurred in excised membrane patches in the absence of calcium and all nucleotides. Therefore signal transduction pathways that require such soluble factors, including the NADPH-dependent cytochrome P450 pathway, do not mediate the response. Thus, fatty acids directly activate potassium channels and so may constitute a class of signal molecules that regulate ion channels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ordway, R W -- Walsh, J V Jr -- Singer, J J -- DK-31620/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1176-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Massachusetts Medical School, Worcester 01655.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2471269" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arachidonic Acid ; Arachidonic Acids/*pharmacology ; Bufo marinus ; Fatty Acids, Nonesterified/*pharmacology ; In Vitro Techniques ; Ion Channels/drug effects/*physiology ; Kinetics ; Membrane Potentials/drug effects ; Muscle, Smooth/*physiology ; Stomach/physiology
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  • 47
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-12-22
    Description: The contribution of the anticodon to the discrimination between cognate and noncognate tRNAs by Escherichia coli Arg-tRNA synthetase has been investigated by in vitro synthesis and aminoacylation of elongator methionine tRNA (tRNA(mMet) mutants. Substitution of the Arg anticodon CCG for the Met anticodon CAU leads to a dramatic increase in Arg acceptance by tRNA(mMet). A nucleotide (A20) previously identified by others in the dihydrouridine loop of tRNA(Arg)s makes a smaller contribution to the conversion of tRNA(mMet) identity from Met to Arg. The combined anticodon and dihydrouridine loop mutations yield a tRNA(mMet) derivative that is aminoacylated with near-normal kinetics by the Arg-tRNA synthetase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulman, L H -- Pelka, H -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1595-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Developmental Biology and Cancer, Albert Einstein College of Medicine, Bronx, NY 10461.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2688091" target="_blank"〉PubMed〈/a〉
    Keywords: Anticodon/*genetics ; Arginine-tRNA Ligase/metabolism ; Base Sequence ; Escherichia coli/enzymology/genetics ; Kinetics ; Methionine-tRNA Ligase/metabolism ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA, Transfer/*genetics ; RNA, Transfer, Amino Acid-Specific/*genetics ; RNA, Transfer, Arg/*genetics ; Substrate Specificity ; T-Phages/genetics ; Transcription, Genetic
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  • 48
    Publication Date: 1989-06-09
    Description: Vasoactive intestinal peptide (VIP) labeled with 125I, [Tyr10-125I]VIP, can be hydrolyzed by immunoglobulin G (IgG) purified from a human subject, as judged by trichloroacetic acid precipitation and reversed-phase high-performance liquid chromatography (HPLC). The hydrolytic activity was precipitated by antibody to human IgG, it was bound by immobilized protein G and showed a molecular mass close to 150 kilodaltons by gel filtration chromatography, properties similar to those of authentic IgG. The Fab fragment, prepared from IgG by papain treatment, retained the VIP hydrolytic activity of the IgG. Peptide fragments produced by treatment of VIP with the antibody fraction were purified by reversed-phase HPLC and identified by fast atom bombardment-mass spectrometry and peptide sequencing. The scissile bond in VIP deduced from these experiments was Gln16-Met17. The antibody concentration (73.4 fmol per milligram of IgG) and the Kd (0.4 nM) were computed from analysis of VIP binding under conditions that did not result in peptide hydrolysis. Analysis of the antibody-mediated VIP hydrolysis at varying concentrations of substrate suggested conformity with Michaelis-Menton kinetics (Km). The values for Km (37.9 X 10(-9) M) and the turnover number kcat (15.6 min-1) suggested relatively tight VIP binding and a moderate catalytic efficiency of the antibody.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Paul, S -- Volle, D J -- Beach, C M -- Johnson, D R -- Powell, M J -- Massey, R J -- HL 35506/HL/NHLBI NIH HHS/ -- HL 40348/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1158-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Nebraska Medical Center, Omaha 68105.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727702" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *Autoantibodies ; Catalysis ; Chromatography, High Pressure Liquid ; Humans ; Hydrolysis ; Immunoglobulin Fab Fragments ; *Immunoglobulin G ; Kinetics ; Molecular Sequence Data ; Peptide Fragments/isolation & purification ; Vasoactive Intestinal Peptide/*immunology
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  • 49
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-17
    Description: A phosphonate monoester, m-carboxyphenyl phenylacetamidomethylphosphonate, has been found to be a specific inhibitor of the class C beta-lactamase of Enterobacter cloacae P99. Inactivation is rapid (10(3) per second per molar concentration) and reactivation very slow (2.2 X 10(-6) per second). Apparently concerted with the inactivation, one equivalent (with respect to the enzyme) of m-hydroxybenzoate is released. Reactivation is accelerated by hydroxylamine and benzohydroxamate. This suggests that the loss of enzyme activity is due to phosphonylation of an active site functional group. This discovery holds the promise of a new general class of beta-lactamase inhibitors and, perhaps, antibiotics.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pratt, R F -- New York, N.Y. -- Science. 1989 Nov 17;246(4932):917-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Chemistry Department, Wesleyan University, Middletown, CT 06457.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814513" target="_blank"〉PubMed〈/a〉
    Keywords: Enterobacter/*enzymology ; Enterobacteriaceae/*enzymology ; Hydroxamic Acids/pharmacology ; Hydroxylamine ; Hydroxylamines/pharmacology ; Kinetics ; Organophosphorus Compounds/*pharmacology ; Protein Binding ; *beta-Lactamase Inhibitors
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  • 50
    Publication Date: 1989-04-28
    Description: The rapid transductional sequences initiated by interferon-gamma (IFN-gamma) on binding to its receptor regulate functional and genomic responses in many cells but are not well defined. Induction of macrophage activation is an example of such functional and genomic changes in response to IFN-gamma. Addition of IFN-gamma to murine macrophages, at activating concentrations, produced rapid (within 60 seconds) alkalinization of the cytosol and a concomitant, rapid influx of 22Na+. Amiloride inhibited the ion fluxes and the accumulation of specific messenger RNA for two genes induced by IFN-gamma (the early gene JE and the beta chain of the class II major histocompatibility complex gene I-A). The data indicate that IFN-gamma initiates rapid exchange of Na+ and H+ by means of the Na+/H+ antiporter and that these amiloride-sensitive ion fluxes are important to some of the genomic effects of IFN-gamma.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prpic, V -- Yu, S F -- Figueiredo, F -- Hollenbach, P W -- Gawdi, G -- Herman, B -- Uhing, R J -- Adams, D O -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):469-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Duke University Medical Center, Durham, NC 27710.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2541500" target="_blank"〉PubMed〈/a〉
    Keywords: Amiloride/pharmacology ; Animals ; Carrier Proteins/antagonists & inhibitors/metabolism ; Cells, Cultured ; Cytosol/metabolism ; *Gene Expression Regulation ; Histocompatibility Antigens Class II/*genetics ; Hydrogen-Ion Concentration ; Interferon-gamma/*physiology ; Kinetics ; Macrophage Activation ; Macrophages/drug effects/metabolism ; Mice ; *Protons ; RNA, Messenger/biosynthesis ; Sodium/*metabolism ; Sodium-Hydrogen Antiporter
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  • 51
    Publication Date: 1989-08-11
    Description: The endogenous c-mos product, pp39mos, is required for progesterone-induced meiotic maturation in Xenopus oocytes. Treatment of oocytes with progesterone induced a rapid increase in pp39mos that preceded both the activation of maturation promoting factor (MPF) and germinal vesicle breakdown (GVBD). Microinjection of synthetic mos RNA into oocytes activated MPF and induced GVBD in the absence of progesterone. Thus, the mos proto-oncogene product may qualify as a candidate "initiator" protein of MPF and is at least one of the "triggers" for G2 to M transition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sagata, N -- Daar, I -- Oskarsson, M -- Showalter, S D -- Vande Woude, G F -- N01-CO-74101/CO/NCI NIH HHS/ -- New York, N.Y. -- Science. 1989 Aug 11;245(4918):643-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉BRI-Basic Research Program, National Cancer Institute, Frederick Cancer Research Facility, MD 21701.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2474853" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cycloheximide/pharmacology ; Female ; Growth Substances/physiology ; Kinetics ; Maturation-Promoting Factor ; Meiosis/drug effects ; Microinjections ; Oocytes/*physiology ; Progesterone/pharmacology ; Protein Biosynthesis ; Proto-Oncogene Proteins/genetics/*physiology ; Proto-Oncogene Proteins c-mos ; RNA/genetics ; Transcription, Genetic ; Transfection ; Xenopus
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  • 52
    Publication Date: 1989-02-17
    Description: Salmonella bacteria are capable of entering (invading) and multiplying within eukaryotic cells. Stable adherence to and invasion of epithelial cells by S. choleraesuis and S. typhimurium were found to require de novo synthesis of several new bacterial proteins. This inducible event appears to be a coordinately regulated system dependent on trypsin- and neuraminidase-sensitive structures present on the epithelial cell surface. Mutants of S. choleraesuis and S. typhimurium were unable to synthesize these proteins and did not stably adhere to nor invade eukaryotic cells. Two such S. typhimurium mutants were avirulent in mice, an indication that these proteins are required for Salmonella virulence.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finlay, B B -- Heffron, F -- Falkow, S -- AI26195/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1989 Feb 17;243(4893):940-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medical Microbiology, Stanford University School of Medicine, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2919285" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Bacterial Adhesion ; Bacterial Proteins/*biosynthesis ; Cell Line ; Epithelium/physiology ; Kinetics ; Methionine/metabolism ; Salmonella/pathogenicity/*physiology ; Sulfur Radioisotopes
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  • 53
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-12-22
    Description: Analysis of crosslinked complexes of M1 RNA, the catalytic RNA subunit of ribonuclease P from Escherichia coli, and transfer RNA precursor substrates has led to the identification of regions in the enzyme and in the substrate that are in close physical proximity to each other. The nucleotide in M1 RNA, residue C92, which participates in a crosslink with the substrate was deleted and the resulting mutant M1 RNA was shown to cleave substrates lacking the 3' terminal CCAUCA sequence at sites several nucleotides away from the normal site of cleavage. The presence or absence of the 3' terminal CCAUCA sequence in transfer RNA precursor substrates markedly affects the way in which these substrates interact with the catalytic RNA in the enzyme-substrate complex. The contacts between wild-type M1 RNA and its substrate are in a region that resembles part of the transfer RNA "E" (exit) site in 23S ribosomal RNA. These data demonstrate that in RNA's with very different cellular functions, there are domains with similar structural and functional properties and that there is a nucleotide in M1 RNA that affects the site of cleavage by the enzyme.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guerrier-Takada, C -- Lumelsky, N -- Altman, S -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1578-84.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Yale University, New Haven, CT 06520.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2480641" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Endoribonucleases/genetics/*metabolism ; Escherichia coli/enzymology/*genetics ; *Escherichia coli Proteins ; Kinetics ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA Precursors/genetics ; RNA, Bacterial/*genetics/metabolism ; RNA, Transfer/genetics ; Ribonuclease P ; Substrate Specificity
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  • 54
    Publication Date: 1989-05-12
    Description: The intervening sequence of the ribosomal RNA precursor of Tetrahymena is a catalytic RNA molecule, or ribozyme. Acting as a sequence-specific endoribonuclease, it cleaves single-stranded RNA substrates with concomitant addition of guanosine. The chemistry of the reaction has now been studied by introduction of a single phosphorothioate in the substrate RNA at the cleavage site. Kinetic studies show no significant effect of this substitution on kcat (rate constant) or Km (Michaelis constant), providing evidence that some step other than the chemical step is rate-limiting. Product analysis reveals that the reaction proceeds with inversion of configuration at phosphorus, consistent with an in-line, SN2 (P) mechanism. Thus, the ribozyme reaction is in the same mechanistic category as the individual displacement reactions catalyzed by protein nucleotidyltransferases, phosphotransferases, and nucleases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McSwiggen, J A -- Cech, T R -- GM28039/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 May 12;244(4905):679-83.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2470150" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Guanosine/metabolism ; Hydrolysis ; Kinetics ; Molecular Conformation ; Phosphates/metabolism ; Phosphorus ; RNA/*metabolism ; RNA Precursors/*metabolism ; RNA Splicing ; RNA, Catalytic ; RNA, Ribosomal/*metabolism ; Tetrahymena/*genetics ; Thionucleotides/metabolism
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  • 55
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-02
    Description: Double-stranded (ds) RNA and many viruses are inducers of interferon (IFN), the latter presumably because they contain, or can form, dsRNA. Concomitant with the induction of IFN in chicken embryo cells was the induction of a novel double-stranded ribonuclease (dsRNase), which was released into the medium and continued to accumulate long after IFN production ceased. Only avian cells (chicken, quail, turkey, or duck) expressed high levels of this dsRNase; mammalian, turtle, or fish cells did not. Production of the nuclease was inducer dose-dependent. Optimum pH and cation requirements distinguished it from other dsRNase activities. Degradation of dsRNA was endonucleolytic. Activity resided in a molecule of an Mr of approximately 34,500. Low levels of a single-stranded (ss) RNase activity were inseparable from the dsRNase. The role for a dsRNA-inducible dsRNase released from cells is unknown.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meegan, J M -- Marcus, P I -- AI18381/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 2;244(4908):1089-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, The University of Connecticut, Storrs 06269.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2471268" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Birds/embryology/*metabolism ; Cations ; Chick Embryo ; Ducks/embryology ; Endoribonucleases/*biosynthesis ; Enzyme Induction ; Hydrogen-Ion Concentration ; Interferon Inducers/pharmacology ; Interferons/*metabolism ; Kinetics ; Newcastle disease virus/physiology/radiation effects ; Poly I-C/pharmacology ; Quail/embryology ; RNA, Double-Stranded/metabolism ; Species Specificity ; Substrate Specificity ; Turkeys/embryology ; Ultraviolet Rays
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  • 56
    Publication Date: 1989-05-12
    Description: Methotrexate coupled to maleylated bovine serum albumin was taken up efficiently through the "scavenger" receptors present on macrophages and led to selective killing of intracellular Leishmania mexicana amazonensis amastigotes in cultured hamster peritoneal macrophages. The drug conjugate was nearly 100 times as effective as free methotrexate in eliminating the intracellular parasites. Furthermore, in a model of experimental cutaneous leishmaniasis in hamsters, the drug conjugate brought about more than 90% reduction in the size of footpad lesions within 11 days. In contrast, the free drug at a similar concentration did not significantly affect lesion size. These studies demonstrate the potential of receptor-mediated drug delivery in the therapy of macrophage-associated diseases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mukhopadhyay, A -- Chaudhuri, G -- Arora, S K -- Sehgal, S -- Basu, S K -- New York, N.Y. -- Science. 1989 May 12;244(4905):705-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Microbial Technology, Chandigarh, India.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2717947" target="_blank"〉PubMed〈/a〉
    Keywords: Albumins/*administration & dosage/metabolism ; Animals ; Cells, Cultured ; Cricetinae ; Female ; Kinetics ; Leishmania mexicana/*drug effects ; Leishmaniasis/*drug therapy ; Macrophages/metabolism/*parasitology ; Male ; *Membrane Proteins ; Mesocricetus ; Methotrexate/*administration & dosage/pharmacology/therapeutic use ; *Receptors, Immunologic/metabolism ; *Receptors, Lipoprotein ; Receptors, Scavenger ; Scavenger Receptors, Class B ; Serum Albumin, Bovine
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  • 57
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-12-22
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schwarz, S -- Pohl, P -- Zhou, G Z -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1635-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2556797" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding, Competitive ; Brain/metabolism ; Kinetics ; Ligands ; Lymphocytes/metabolism ; Progesterone/blood/cerebrospinal fluid/metabolism ; Receptors, Opioid/*metabolism ; Receptors, sigma ; Steroids/*metabolism/pharmacology
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  • 58
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-10-06
    Description: A microscopic method for simulating quantum mechanical, nuclear tunneling effects in biological electron transfer reactions is presented and applied to several electron transfer steps in photosynthetic bacterial reaction centers. In this "dispersed polaron" method the fluctuations of the protein and the electron carriers are projected as effective normal modes onto an appropriate reaction coordinate and used to evaluate the quantum mechanical rate constant. The simulations, based on the crystallographic structure of the reaction center from Rhodopseudomonas viridis, focus on electron transfer from a bacteriopheophytin to a quinone and the subsequent back-reaction. The rates of both of these reactions are almost independent of temperature or even increase with decreasing temperature. The simulations reproduce this unusual temperature dependence in a qualitative way, without the use of adjustable parameters for the protein's Franck-Condon factors. The observed dependence of the back-reaction on the free energy of the reaction also is reproduced, including the special behavior in the "inverted region."〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Warshel, A -- Chu, Z T -- Parson, W W -- GM-40283/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Oct 6;246(4926):112-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Southern California, Los Angeles 90007.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2675313" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*metabolism ; *Electron Transport ; Kinetics ; Models, Chemical ; *Photosynthesis ; Photosynthetic Reaction Center Complex Proteins ; Rhodopseudomonas/metabolism ; Thermodynamics
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  • 59
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-17
    Description: A true Bronsted analysis of proton transfer in an enzyme mechanism is made possible by the chemical rescue of an inactive mutant of aspartate aminotransferase, where the endogenous general base, Lys258, is replaced with Ala by site-directed mutagenesis. Catalytic activity is restored to this inactive mutant by exogenous amines. The eleven amines studied generate a Bronsted correlation with beta of 0.4 for the transamination of cysteine sulfinate, when steric effects are included in the regression analysis. Localized mutagenesis thus allows the classical Bronsted analysis of transition-state structure to be applied to enzyme-catalyzed reactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Toney, M D -- Kirsch, J F -- GM07232/GM/NIGMS NIH HHS/ -- GM35393/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Mar 17;243(4897):1485-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2538921" target="_blank"〉PubMed〈/a〉
    Keywords: Amines ; Aspartate Aminotransferases/*metabolism ; Binding Sites ; Catalysis ; Escherichia coli/enzymology ; Kinetics ; Lysine ; Mutation ; Protons
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  • 60
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-02-24
    Description: Gadolinium ions produce three distinct kinds of block of the stretch-activated (SA) ion channels in Xenopus oocytes: a concentration-dependent reduction in channel open time, a concentration-dependent reduction in open channel current, and a unique, steeply concentration-dependent, reversible inhibition of channel opening. This last effect reduces the probability of a channel being open from about 10(-1) at 5 microM to less than 10(-5) at 10 microM gadolinium. Calcium has effects on open time and current similar to that of gadolinium, but this channel is permeable to calcium and calcium does not completely inhibit channel activity. The availability of a blocker for SA ion channels may help to define their physiological function, and will simplify the use of oocytes as an expression system for ion channels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yang, X C -- Sachs, F -- DK-37792/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Feb 24;243(4894 Pt 1):1068-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State University of New York, Buffalo 14214.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2466333" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding, Competitive ; Calcium/*pharmacology ; Cations ; Electric Conductivity ; Female ; Gadolinium/*pharmacology ; Ion Channels/drug effects/*physiology ; Kinetics ; Oocytes/*physiology ; Xenopus
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  • 61
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-07-07
    Description: beta-Adrenergic agonists activate the G protein, Gs, which stimulates cardiac calcium currents by both cytoplasmic, indirect and membrane-delimited, direct pathways. To test whether beta-adrenergic agonists might use both pathways in the heart, isoproterenol was rapidly applied to cardiac myocytes, resulting in a biphasic increase in cardiac calcium channel currents that had time constants of 150 milliseconds and 36 seconds. beta-Adrenergic antagonists of a G protein inhibitor blocked both the fast and slow responses, whereas the adenylyl cyclase activator forskolin produced only the slow response. The presence of a fast pathway in the heart can explain what the slow pathway cannot account for: the ability of cardiac sympathetic nerves to change heart rate within a single beat.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yatani, A -- Brown, A M -- HL36930/HL/NHLBI NIH HHS/ -- HL37044/HL/NHLBI NIH HHS/ -- NS23877/NS/NINDS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1989 Jul 7;245(4913):71-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2544999" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atrial Function ; Calcium Channels/drug effects/*physiology ; Carbachol/pharmacology ; Cells, Cultured ; Colforsin/pharmacology ; GTP-Binding Proteins/*physiology ; Guinea Pigs ; Heart/*physiology ; Isoproterenol/*pharmacology ; Kinetics ; Membrane Potentials/drug effects ; *Signal Transduction
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  • 62
    Publication Date: 1989-11-03
    Description: Many Gram-negative bacteria export proteins to the exterior. Some of these proteins are first secreted into the periplasm and then cross the outer membrane in a separate step. The source of energy required for the translocation is unknown. Export of the extracellular protein proaerolysin from the periplasm through the outer membrane of Aeromonas salmonicida is inhibited by a proton ionophore and by low extracellular pH. One possible explanation of these results is that a proton gradient across the outer membrane is required for export.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wong, K R -- Buckley, J T -- New York, N.Y. -- Science. 1989 Nov 3;246(4930):654-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Microbiology, University of Victoria, BC, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814486" target="_blank"〉PubMed〈/a〉
    Keywords: Aeromonas/drug effects/*metabolism ; Bacterial Toxins/*metabolism ; Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology ; Cell Membrane/metabolism ; Culture Media ; Hemolysin Proteins/*metabolism ; Hydrogen-Ion Concentration ; Kinetics ; Pore Forming Cytotoxic Proteins
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  • 63
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-01-10
    Description: In vivo, cytoplasmic microtubules are nucleated and anchored by their minus ends at the centrosome and are believed to turn over by a mechanism termed dynamic instability: depolymerization and repolymerization at their plus ends. In cytoplasmic fragments of fish melanophores, microtubules were shown to detach from their nucleation site and depolymerize from their minus ends. Free microtubules moved toward the periphery by treadmilling-growth at one end and shortening from the opposite end. Frequent release from nucleation sites may be a general property of centrosomes and permit a minus-end mechanism of microtubule turnover and treadmilling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rodionov, V I -- Borisy, G G -- GM25062/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jan 10;275(5297):215-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Biology, University of Wisconsin, Madison, WI 53706, USA. ggborisy@facstaf.wisc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8985015" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Membrane/metabolism ; Cells, Cultured ; Centrosome/metabolism ; Cytoplasm/metabolism/ultrastructure ; Fishes ; Kinetics ; Melanophores/ultrastructure ; Microtubules/metabolism/*physiology/ultrastructure ; Movement ; Pigments, Biological/metabolism ; Polymers
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 64
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-11-14
    Description: Palmitoylation of the alpha subunit of the guanine nucleotide-binding protein Gz inhibited by more than 90 percent its response to the guanosine triphosphatase (GTPase)-accelerating activity of Gz GAP, a Gz-selective member of the regulators of G-protein signaling (RGS) protein family of GTPase-activating proteins (GAPs). Palmitoylation both decreased the affinity of Gz GAP for the GTP-bound form of Galphaz by at least 90 percent and decreased the maximum rate of GTP hydrolysis. Inhibition was reversed by removal of the palmitoyl group by dithiothreitol. Palmitoylation of Galphaz also inhibited its response to the GAP activity of Galpha-interacting protein (GAIP), another RGS protein, and palmitoylation of Galphai1 inhibited its response to RGS4. The extent of inhibition of Gz GAP, GAIP, RGS4, and RGS10 correlated roughly with their intrinsic GAP activities for the Galpha target used in the assay. Reversible palmitoylation is thus a major determinant of Gz deactivation after its stimulation by receptors, and may be a general mechanism for prolonging or potentiating G-protein signaling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tu, Y -- Wang, J -- Ross, E M -- GM30355/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Nov 7;278(5340):1132-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-9041, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9353196" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; Dithiothreitol/pharmacology ; *GTP-Binding Protein alpha Subunits ; GTP-Binding Proteins/*metabolism ; GTPase-Activating Proteins ; Guanosine 5'-O-(3-Thiotriphosphate)/metabolism ; Guanosine Triphosphate/metabolism ; *Heterotrimeric GTP-Binding Proteins ; Hydrolysis ; Kinetics ; Palmitic Acid/*metabolism ; Palmitoyl Coenzyme A/metabolism ; Phosphoproteins/antagonists & inhibitors/metabolism ; Proteins/*antagonists & inhibitors/metabolism ; *RGS Proteins ; Signal Transduction
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  • 65
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-09-26
    Description: In plants and algae, photosystem II uses light energy to oxidize water to oxygen at a metalloradical site that comprises a tetranuclear manganese cluster and a tyrosyl radical. A model is proposed whereby the tyrosyl radical functions by abstracting hydrogen atoms from substrate water bound as terminal ligands to two of the four manganese ions. Molecular oxygen is produced in the final step in which hydrogen atom transfer and oxygen-oxygen bond formation occur together in a concerted reaction. This mechanism establishes clear analogies between photosynthetic water oxidation and amino acid radical function in other enzymatic reactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hoganson, C W -- Babcock, G T -- GM-37300/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 26;277(5334):1953-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Michigan State University, East Lansing, MI 48824-1322, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9302282" target="_blank"〉PubMed〈/a〉
    Keywords: Electrons ; Eukaryota/metabolism ; Hydrogen/metabolism ; Kinetics ; Ligands ; Manganese/*metabolism ; Models, Chemical ; Oxidation-Reduction ; Oxygen/*metabolism ; *Photosynthesis ; Photosynthetic Reaction Center Complex Proteins/*metabolism ; Photosystem II Protein Complex ; Plants/metabolism ; Tyrosine/*metabolism ; Water/*metabolism
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  • 66
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-02-07
    Description: Calcium signals were recorded from glial cells in acutely isolated rat retina to determine whether Ca2+ waves occur in glial cells of intact central nervous system tissue. Chemical (adenosine triphosphate), electrical, and mechanical stimulation of astrocytes initiated increases in the intracellular concentration of Ca2+ that propagated at approximately 23 micrometers per second through astrocytes and Muller cells as intercellular waves. The Ca2+ waves persisted in the absence of extracellular Ca2+ but were largely abolished by thapsigargin and intracellular heparin, indicating that Ca2+ was released from intracellular stores. The waves did not evoke changes in cell membrane potential but traveled synchronously in astrocytes and Muller cells, suggesting a functional linkage between these two types of glial cells. Such glial Ca2+ waves may constitute an extraneuronal signaling pathway in the central nervous system.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2410141/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2410141/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Newman, E A -- Zahs, K R -- EY04077/EY/NEI NIH HHS/ -- EY10383/EY/NEI NIH HHS/ -- R01 EY004077/EY/NEI NIH HHS/ -- R01 EY004077-19/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1997 Feb 7;275(5301):844-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Minnesota, 435 Delaware Street, SE, Minneapolis, MN 55455, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9012354" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/pharmacology ; Animals ; Astrocytes/*metabolism ; Calcium/*metabolism ; Calcium Channels/metabolism ; Electric Stimulation ; Heparin/pharmacology ; In Vitro Techniques ; Inositol 1,4,5-Trisphosphate Receptors ; Kinetics ; Membrane Potentials ; Neuroglia/*metabolism ; Physical Stimulation ; Rats ; Receptors, Cytoplasmic and Nuclear/metabolism ; Retina/*cytology/metabolism ; Signal Transduction ; Stimulation, Chemical ; Thapsigargin/pharmacology
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  • 67
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-09-05
    Description: The role of postsynaptic, neuronal glutamate transporters in terminating signals at central excitatory synapses is not known. Stimulation of a climbing fiber input to cerebellar Purkinje cells was shown to generate an anionic current mediated by glutamate transporters. The kinetics of transporter currents were resolved by pulses of glutamate to outside-out membrane patches from Purkinje cells. Comparison of synaptic transporter currents to transporter currents expressed in Xenopus oocytes suggests that postsynaptic uptake at the climbing fiber synapse removes at least 22 percent of released glutamate. These neuronal transporter currents arise from synchronous activation of transporters that greatly outnumber activated AMPA receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Otis, T S -- Kavanaugh, M P -- Jahr, C E -- NS21419/NS/NINDS NIH HHS/ -- NS33270/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 5;277(5331):1515-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Vollum Institute, L-474, Oregon Health Sciences University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97201, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9278516" target="_blank"〉PubMed〈/a〉
    Keywords: *Amino Acid Transport System X-AG ; Animals ; Aspartic Acid/analogs & derivatives/pharmacology ; Biological Transport ; Carrier Proteins/*metabolism ; Dicarboxylic Acids/pharmacology ; Glutamate Plasma Membrane Transport Proteins ; Glutamic Acid/*metabolism ; In Vitro Techniques ; Kinetics ; Nerve Fibers/*metabolism ; Oocytes ; Patch-Clamp Techniques ; Purkinje Cells/*metabolism ; Pyrrolidines/pharmacology ; Rats ; Receptors, AMPA/metabolism ; Receptors, Glutamate/*metabolism ; *Symporters ; Synapses/*metabolism ; *Synaptic Transmission ; Xenopus
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  • 68
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-05-09
    Description: A mechanism is proposed to explain the activity of orotidine 5'-monophosphate decarboxylase (ODCase). This enzyme is the one of the most proficient known, with a catalytic proficiency (kcat/Km)/knon = 10(23) M-1. Quantum mechanical calculations predict a mechanism involving a stabilized carbene intermediate, which represents a previously unrecognized mode of enzymatic activity for ODCase. The proposed mechanism involves proton transfer from a weak acid (pKa = 7, where Ka is the acid constant) concerted with decarboxylation, in a nonpolar enzyme environment. Such a mechanism makes possible different approaches to the design of ODCase inhibitors. Furthermore, the prediction that general acid catalysis may only be effective in low dielectric media is of general significance for understanding the activity of many enzymes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, J K -- Houk, K N -- New York, N.Y. -- Science. 1997 May 9;276(5314):942-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9139656" target="_blank"〉PubMed〈/a〉
    Keywords: Barbiturates/pharmacology ; Binding Sites ; Catalysis ; Decarboxylation ; Enzyme Inhibitors/pharmacology ; Hydrogen-Ion Concentration ; Kinetics ; Orotidine-5'-Phosphate Decarboxylase/antagonists & inhibitors/*metabolism ; Protons ; Thermodynamics ; Uridine Monophosphate/*analogs & derivatives/metabolism
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  • 69
    Publication Date: 1997-05-09
    Description: In lymphoid tissue, where human immunodeficiency virus-type 1 (HIV-1) is produced and stored, three-drug treatment with viral protease and reverse transcriptase inhibitors markedly reduced viral burden. This was shown by in situ hybridization and computerized quantitative analysis of serial tonsil biopsies from previously untreated adults. The frequency of productive mononuclear cells (MNCs) initially diminished with a half-life of about 1 day. Surprisingly, the amount of HIV-1 RNA in virus trapped on follicular dendritic cells (FDCs) decreased almost as quickly. After 24 weeks, MNCs with very few copies of HIV-1 RNA per cell were still detectable, as was proviral DNA; however, the amount of FDC-associated virus decreased by 〉/=3.4 log units. Thus, 6 months of potent therapy controlled active replication and cleared 〉99.9 percent of virus from the secondary lymphoid tissue reservoir.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cavert, W -- Notermans, D W -- Staskus, K -- Wietgrefe, S W -- Zupancic, M -- Gebhard, K -- Henry, K -- Zhang, Z Q -- Mills, R -- McDade, H -- Schuwirth, C M -- Goudsmit, J -- Danner, S A -- Haase, A T -- AI 25017/AI/NIAID NIH HHS/ -- AI 28246/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1997 May 9;276(5314):960-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9139661" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Anti-HIV Agents/*therapeutic use ; CD4-Positive T-Lymphocytes/virology ; DNA, Viral/analysis ; Dendritic Cells/cytology/*virology ; Drug Therapy, Combination ; HIV Infections/*drug therapy/virology ; HIV Protease Inhibitors/therapeutic use ; HIV-1/*drug effects/isolation & purification/physiology ; Humans ; Image Processing, Computer-Assisted ; In Situ Hybridization ; Kinetics ; Lamivudine/therapeutic use ; Leukocytes, Mononuclear/cytology/*virology ; Macrophages/virology ; Palatine Tonsil/*virology ; Proviruses/genetics ; RNA, Viral/analysis ; Reverse Transcriptase Inhibitors/therapeutic use ; Ritonavir/therapeutic use ; Viral Load ; Virus Replication/drug effects ; Zidovudine/therapeutic use
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  • 70
    Publication Date: 1998-05-23
    Description: Tris(vancomycin carboxamide) binds a trivalent ligand derived from D-Ala-D-Ala with very high affinity: dissociation constant (Kd) approximately 4 x 10(-17) +/- 1 x 10(-17) M. High-affinity trivalent binding and monovalent binding are fundamentally different. In trivalent (and more generally, polyvalent) binding, dissociation occurs in stages, and its rate can be accelerated by monovalent ligand at sufficiently high concentrations. In monovalent binding, dissociation is determined solely by the rate constant for dissociation and cannot be accelerated by added monomer. Calorimetric measurements for the trivalent system indicate an approximately additive gain in enthalpy relative to the corresponding monomers. This system is one of the most stable organic receptor-ligand pairs involving small molecules that is known. It illustrates the practicality of designing very high-affinity systems based on polyvalency.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rao, J -- Lahiri, J -- Isaacs, L -- Weis, R M -- Whitesides, G M -- GM 30367/GM/NIGMS NIH HHS/ -- GM 51559/GM/NIGMS NIH HHS/ -- GM 53210/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 May 1;280(5364):708-11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9563940" target="_blank"〉PubMed〈/a〉
    Keywords: Alanine/*analogs & derivatives/chemistry/metabolism ; Avidin/metabolism ; Biotin/metabolism ; Calorimetry ; Chromatography, High Pressure Liquid ; Dipeptides/chemistry/*metabolism ; Kinetics ; Ligands ; Thermodynamics ; Vancomycin/*analogs & derivatives/chemistry/*metabolism
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  • 71
    Publication Date: 1997-08-15
    Description: Epoxides are versatile building blocks for organic synthesis. However, terminal epoxides are arguably the most important subclass of these compounds, and no general and practical method exists for their production in enantiomerically pure form. Terminal epoxides are available very inexpensively as racemic mixtures, and kinetic resolution is an attractive strategy for the production of optically active epoxides, given an economical and operationally simple method. Readily accessible synthetic catalysts (chiral cobalt-based salen complexes) have been used for the efficient asymmetric hydrolysis of terminal epoxides. This process uses water as the only reagent, no added solvent, and low loadings of a recyclable catalyst (〈0.5 mole percent), and it affords highly valuable terminal epoxides and 1, 2-diols in high yield with high enantiomeric enrichment.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tokunaga, M -- Larrow, J F -- Kakiuchi, F -- Jacobsen, E N -- GM-43214/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Aug 15;277(5328):936-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9252321" target="_blank"〉PubMed〈/a〉
    Keywords: *Catalysis ; Epoxy Compounds/*chemistry/isolation & purification ; Hydrolysis ; Kinetics ; Stereoisomerism ; Water/*chemistry
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  • 72
    Publication Date: 1997-01-17
    Description: The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselves and thus some other agent must exist. A 78-kilodalton protein has been isolated that, in the presence of an oxidase or one electron oxidant, effects stereoselective bimolecular phenoxy radical coupling in vitro. Itself lacking a catalytically active (oxidative) center, its mechanism of action is presumed to involve capture of E-coniferyl alcohol-derived free-radical intermediates, with consequent stereoselective coupling to give (+)-pinoresinol.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Davin, L B -- Wang, H B -- Crowell, A L -- Bedgar, D L -- Martin, D M -- Sarkanen, S -- Lewis, N G -- New York, N.Y. -- Science. 1997 Jan 17;275(5298):362-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8994027" target="_blank"〉PubMed〈/a〉
    Keywords: Dimerization ; Flavin Mononucleotide/metabolism ; Flavin-Adenine Dinucleotide/metabolism ; Free Radicals ; Furans/chemistry/*metabolism ; Kinetics ; Laccase ; Lignans/*biosynthesis/chemistry ; Molecular Conformation ; Oxidation-Reduction ; Oxidoreductases/chemistry/*metabolism ; Phenols/chemistry/*metabolism ; Plant Proteins/*metabolism ; Stereoisomerism
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  • 73
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-01-17
    Description: The kinetic mechanism by which the DNA repair helicase UvrD of Escherichia coli unwinds duplex DNA was examined with the use of a series of oligodeoxynucleotides with duplex regions ranging from 10 to 40 base pairs. Single-turnover unwinding experiments showed distinct lag phases that increased with duplex length because partially unwound DNA intermediate states are highly populated during unwinding. Analysis of these kinetics indicates that UvrD unwinds duplex DNA in discrete steps, with an average "step size" of 4 to 5 base pairs (approximately one-half turn of the DNA helix). This suggests an unwinding mechanism in which alternating subunits of the dimeric helicase interact directly with duplex DNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ali, J A -- Lohman, T M -- GM45948/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jan 17;275(5298):377-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8994032" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/*metabolism ; Adenosine Triphosphate/metabolism ; Base Composition ; DNA/chemistry/*metabolism ; DNA Helicases/*metabolism ; DNA, Single-Stranded/metabolism ; Escherichia coli/*enzymology ; Escherichia coli Proteins ; Kinetics ; *Nucleic Acid Conformation ; Oligodeoxyribonucleotides/chemistry/*metabolism
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  • 74
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-06-13
    Description: The extent to which inositol 1,4,5-trisphosphate (InsP3)-induced calcium signals are localized is a critical parameter for understanding the mechanism of effector activation. The spatial characteristics of InsP3-mediated calcium signals were determined by targeting a dextran-based calcium indicator to intracellular membranes through the in situ addition of a geranylgeranyl lipid group. Elementary calcium-release events observed with this indicator typically lasted less than 33 milliseconds, had diameters less than 2 micrometers, and were uncoupled from each other by the calcium buffer EGTA. Cellwide calcium transients are likely to result from synchronized triggering of such local release events, suggesting that calcium-dependent effector proteins could be selectively activated by localization near sites of local calcium release.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Horne, J H -- Meyer, T -- GM-51457/GM/NIGMS NIH HHS/ -- P01-HL-47053/HL/NHLBI NIH HHS/ -- R01-GM-48113/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jun 13;276(5319):1690-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9180077" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Calcium Channels/metabolism ; Cytosol/metabolism ; Egtazic Acid/pharmacology ; Electroporation ; Fluorescent Dyes ; Inositol 1,4,5-Trisphosphate/*pharmacology ; Intracellular Membranes/*metabolism ; Kinetics ; Microscopy, Confocal ; Microscopy, Fluorescence ; Organic Chemicals ; Peptides/metabolism ; Rats ; Signal Transduction ; Tumor Cells, Cultured
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  • 75
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-05-09
    Description: Nonequilibrium fluctuations, whether generated externally or by a chemical reaction far from equilibrium, can bias the Brownian motion of a particle in an anisotropic medium without thermal gradients, a net force such as gravity, or a macroscopic electric field. Fluctuation-driven transport is one mechanism by which chemical energy can directly drive the motion of particles and macromolecules and may find application in a wide variety of fields, including particle separation and the design of molecular motors and pumps.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Astumian, R D -- R29ES06620/ES/NIEHS NIH HHS/ -- New York, N.Y. -- Science. 1997 May 9;276(5314):917-22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Surgery, University of Chicago, MC6035, Chicago, IL 60637, USA. dastumia@surgery.bsd.uchicago.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9139648" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Anisotropy ; Chemistry, Physical ; Diffusion ; Ion Pumps/*metabolism ; Kinetics ; Mathematics ; *Motion ; Particle Size ; Physicochemical Phenomena ; Sodium-Potassium-Exchanging ATPase/metabolism ; Stochastic Processes ; *Thermodynamics
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 76
    Publication Date: 1998-02-12
    Description: Structural and mechanistic studies show that when the selection criteria of the immune system are changed, catalytic antibodies that have the efficiency of natural enzymes evolve, but the catalytic antibodies are much more accepting of a wide range of substrates. The catalytic antibodies were prepared by reactive immunization, a process whereby the selection criteria of the immune system are changed from simple binding to chemical reactivity. This process yielded aldolase catalytic antibodies that approximated the rate acceleration of the natural enzyme used in glycolysis. Unlike the natural enzyme, however, the antibody aldolases catalyzed a variety of aldol reactions and decarboxylations. The crystal structure of one of these antibodies identified the reactive lysine residue that was selected in the immunization process. This lysine is deeply buried in a hydrophobic pocket at the base of the binding site, thereby accounting for its perturbed pKa.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barbas, C F 3rd -- Heine, A -- Zhong, G -- Hoffmann, T -- Gramatikova, S -- Bjornestedt, R -- List, B -- Anderson, J -- Stura, E A -- Wilson, I A -- Lerner, R A -- CA27489/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1997 Dec 19;278(5346):2085-92.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Skaggs Institute for Chemical Biology and the Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9405338" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Catalytic/chemistry/immunology/*metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Decarboxylation ; *Evolution, Molecular ; Fructose-Bisphosphate Aldolase/chemistry/immunology/*metabolism ; Glycolysis ; Hydrogen-Ion Concentration ; Immunization ; Immunoglobulin Fab Fragments/chemistry/immunology/*metabolism ; Kinetics ; Lysine/chemistry/metabolism ; Mice ; Models, Molecular ; Protein Conformation ; Pyridoxal/metabolism ; Selection, Genetic ; Substrate Specificity
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  • 77
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-08-15
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ronaghi, M -- Uhlen, M -- Nyren, P -- New York, N.Y. -- Science. 1998 Jul 17;281(5375):363, 365.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biotechnology, The Royal Institute of Technology, SE-10044 Stockholm, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9705713" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Apyrase/metabolism ; Automation ; DNA/biosynthesis ; DNA Primers ; DNA-Directed DNA Polymerase/metabolism ; Deoxyribonucleotides/metabolism ; Diphosphates/*metabolism ; Kinetics ; Light ; Luciferases/metabolism ; Polymerase Chain Reaction ; Sequence Analysis, DNA/*methods ; Sulfate Adenylyltransferase/metabolism ; Templates, Genetic
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  • 78
    Publication Date: 1998-03-21
    Description: NSF (N-ethylmaleimide-sensitive factor) is an adenosine triphosphatase (ATPase) that contributes to a protein complex essential for membrane fusion. The synaptic function of this protein was investigated by injecting, into the giant presynaptic terminal of squid, peptides that inhibit the ATPase activity of NSF stimulated by the soluble NSF attachment protein (SNAP). These peptides reduced the amount and slowed the kinetics of neurotransmitter release as a result of actions that required vesicle turnover and occurred at a step subsequent to vesicle docking. These results define NSF as an essential participant in synaptic vesicle exocytosis that regulates the kinetics of neurotransmitter release and, thereby, the integrative properties of synapses.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schweizer, F E -- Dresbach, T -- DeBello, W M -- O'Connor, V -- Augustine, G J -- Betz, H -- New York, N.Y. -- Science. 1998 Feb 20;279(5354):1203-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9469810" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/antagonists & inhibitors/metabolism ; Amino Acid Sequence ; Animals ; Calcium/metabolism ; Carrier Proteins/chemistry/*metabolism/pharmacology ; Decapodiformes ; Excitatory Postsynaptic Potentials ; Exocytosis ; Glutamic Acid/metabolism ; Kinetics ; Membrane Fusion ; Membrane Proteins/pharmacology ; Molecular Sequence Data ; N-Ethylmaleimide-Sensitive Proteins ; Neurotransmitter Agents/*metabolism ; Patch-Clamp Techniques ; Peptide Fragments/pharmacology ; Presynaptic Terminals/*metabolism ; Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins ; Synaptic Transmission ; Synaptic Vesicles/*metabolism/physiology ; *Vesicular Transport Proteins
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  • 79
    Publication Date: 1998-04-16
    Description: Radiolysis of water with a synchrotron x-ray beam permits the hydroxyl radical-accessible surface of an RNA to be mapped with nucleotide resolution in 10 milliseconds. Application of this method to folding of the Tetrahymena ribozyme revealed that the most stable domain of the tertiary structure, P4-P6, formed cooperatively within 3 seconds. Exterior helices became protected from hydroxyl radicals in 10 seconds, whereas the catalytic center required minutes to be completely folded. The results show that rapid collapse to a partially disordered state is followed by a slow search for the active structure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sclavi, B -- Sullivan, M -- Chance, M R -- Brenowitz, M -- Woodson, S A -- GM39929/GM/NIGMS NIH HHS/ -- GM51506/GM/NIGMS NIH HHS/ -- GM52348/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1998 Mar 20;279(5358):1940-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Biophysics, Center for Synchrotron Biosciences, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9506944" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Hydroxyl Radical ; Kinetics ; Magnesium ; Models, Molecular ; *Nucleic Acid Conformation ; RNA, Catalytic/*chemistry ; Solvents ; Synchrotrons ; Tetrahymena/chemistry ; X-Rays
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  • 80
    Publication Date: 1998-04-16
    Description: In the magnesium ion-dependent folding of the Tetrahymena ribozyme, a kinetic intermediate accumulates in which the P4-P6 domain is formed, but the P3-P7 domain is not. The kinetic barriers to P3-P7 formation were investigated with the use of in vitro selection to identify mutant RNA molecules in which the folding rate of the P3-P7 domain was increased. The critical mutations disrupt native tertiary interactions within the P4-P6 domain and increase the rate of P3-P7 formation by destabilizing a kinetically trapped intermediate. Hence, kinetic traps stabilized by native interactions, and not simply by mispaired nonnative structures, can present a substantial barrier to RNA folding.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Treiber, D K -- Rook, M S -- Zarrinkar, P P -- Williamson, J R -- New York, N.Y. -- Science. 1998 Mar 20;279(5358):1943-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, MB33, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9506945" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Kinetics ; Magnesium/metabolism ; Models, Molecular ; Mutation ; *Nucleic Acid Conformation ; RNA, Catalytic/*chemistry/genetics/metabolism ; Tetrahymena/chemistry
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  • 81
    Publication Date: 1998-04-16
    Description: Chemical dynamics in proteins are discussed, with bacteriorhodopsin serving as a model system. Ultrafast time-resolved methods used to probe the chemical dynamics of retinal photoisomerization in bacteriorhodopsin are discussed, along with future prospects for ultrafast time-resolved crystallography. The photoisomerization of retinal in bacteriorhodopsin is far more selective and efficient than in solution, the origins of which are discussed in the context of a three-state model for the photoisomerization reaction coordinate. The chemical dynamics are complex, with the excited-state relaxation exhibiting a multiexponential decay with well-defined rate constants. Possible origins for the two major components are also discussed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gai, F -- Hasson, K C -- McDonald, J C -- Anfinrud, P A -- DK45306/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1998 Mar 20;279(5358):1886-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9506931" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriorhodopsins/*chemistry/metabolism ; Halobacterium salinarum/chemistry/metabolism ; Isomerism ; Kinetics ; *Light ; Models, Chemical ; Protein Conformation ; Retinaldehyde/*chemistry/metabolism ; Spectrum Analysis ; Thermodynamics
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  • 82
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-12-16
    Description: The expression of a laboratory strain of HIV-1 (HTLV-IIIB) has been studied in mitogen-stimulated peripheral blood lymphocytes (PBLs) and in two lymphoid cell lines (CEM cells and C8166 cells). HIV-expressing cells contained from 300,000 to 2,500,000 copies of viral RNA per cell. Near-synchronous expression of an active infection could be achieved in C8166 cells. In these cells, the high copy numbers of viral RNA used as much as 40% of total protein synthesis for the production of viral gag protein, with high levels of viral RNA and protein synthesis preceding cell death by 2 to 4 days.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Somasundaran, M -- Robinson, H L -- AI 24474/AI/NIAID NIH HHS/ -- N01-HB-6-7022/HB/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Dec 16;242(4885):1554-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Massachusetts Medical Center, Worcester 01655.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3201245" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Line ; *Cell Transformation, Viral ; HIV-1/*genetics/growth & development/metabolism ; Humans ; Kinetics ; Lymphocytes/*microbiology ; RNA, Viral/*biosynthesis ; Viral Proteins/*biosynthesis
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  • 83
    Publication Date: 1988-03-18
    Description: The effects of lithium on inositol phosphate metabolism may account for the therapeutic actions of lithium in affective disorder. Muscarinic stimulation of the phosphoinositide system blocks synaptic inhibitory actions of adenosine in the hippocampal slice. At therapeutic concentrations, lithium diminished this muscarinic response, whereas rubidium, which does not affect phosphoinositide metabolism, had no effect. A dampening of phosphoinositide-mediated neurotransmission may explain the normalizing effects of lithium in treating both mania and depression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Worley, P F -- Heller, W A -- Snyder, S H -- Baraban, J M -- DA-00266/DA/NIDA NIH HHS/ -- MH-18501/MH/NIMH NIH HHS/ -- MH-42323/MH/NIMH NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Mar 18;239(4846):1428-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2831626" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine/pharmacology ; Carbachol/pharmacology ; Enzyme Activation/drug effects ; Hippocampus/drug effects/*physiology ; Inositol Phosphates/metabolism ; Kinetics ; Lithium/*pharmacology ; Oxotremorine/analogs & derivatives/pharmacology ; Phorbol Esters/pharmacology ; Phosphatidylinositols/*metabolism ; Protein Kinase C/metabolism ; Receptors, Muscarinic/drug effects/*physiology ; Synapses/physiology ; Synaptic Transmission/drug effects
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  • 84
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-06-24
    Description: A specific, reversible binding site for a free amino acid is detectable on the intron of the Tetrahymena self-splicing ribosomal precursor RNA. The site selects arginine among the natural amino acids, and prefers the L- to the D-amino acid. The dissociation constant is in the millimolar range, and amino acid binding is at or in the catalytic rG splicing substrate site. Occupation of the G site by L-arginine therefore inhibits splicing by inhibiting the binding of rG, without inhibition of later reactions in the splicing reaction sequence. Arginine binding specificity seems to be directed at the side chain and the guanidino radical, and the alpha-amino and carboxyl groups are dispensable for binding. The arginine site can be placed within the G site by structural homology, with consequent implications for RNA-amino acid interaction, for the origin of the genetic code, for control of RNA activities, and for further catalytic capabilities for RNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yarus, M -- R37 GM30881/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 24;240(4860):1751-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3381099" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arginine/*metabolism ; Binding Sites ; Catalysis ; Genetic Code ; Guanosine Triphosphate/metabolism ; Kinetics ; Magnesium/metabolism ; Models, Molecular ; *RNA Splicing ; RNA, Ribosomal/*physiology ; Structure-Activity Relationship ; Tetrahymena
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  • 85
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-02-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zeeberg, B R -- Gibson, R E -- Reba, R C -- MH42821-01/MH/NIMH NIH HHS/ -- NS-15080/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1988 Feb 12;239(4841 Pt 1):789-91.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2963379" target="_blank"〉PubMed〈/a〉
    Keywords: Brain/*metabolism ; Haloperidol/therapeutic use ; Humans ; Kinetics ; Receptors, Dopamine/drug effects/*metabolism ; Receptors, Dopamine D2 ; Schizophrenia/*metabolism
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  • 86
    Publication Date: 1989-05-26
    Description: The eye needs to biosynthesize 11-cis-retinoids because the chromophore of rhodopsin is 11-cis-retinal. The critical metabolic step is the endergonic isomerization of free all-trans-retinol (vitamin A) into 11-cis-retinol. This isomerization process can take place in isolated membranes from the retinal pigment epithelium in the absence of added energy sources. Specific binding proteins probably do not serve as an energy source, and since all of the reactions in the visual cycle are shown here to be reversible, trapping reactions also do not participate in the isomerization reaction. One previously unexplored possibility is that the chemical energy in the bonds of the membrane itself may drive the isomerization reaction. A group transfer reaction is proposed that forms a retinyl ester from a lipid acyl donor and vitamin A. This transfer can drive the isomerization reaction because the all-trans-retinyl ester is isomerized directly to 11-cis-retinol. Thus, the free energy of hydrolysis of the ester is coupled to the thermodynamically uphill trans to cis isomerization. The prediction of an obligate C-O bond cleavage in the vitamin A moiety during isomerization is borne out. Although the natural substrate for isomerization is not known, all-trans-retinyl palmitate is processed in vitro to 11-cis-retinol by pigment epithelial membranes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Deigner, P S -- Law, W C -- Canada, F J -- Rando, R R -- EY04096/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1989 May 26;244(4907):968-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727688" target="_blank"〉PubMed〈/a〉
    Keywords: Amphibians ; Animals ; Cattle ; Cell Membrane/*metabolism ; *Energy Metabolism ; Isomerases/metabolism ; Isomerism ; Kinetics ; Molecular Structure ; Pigment Epithelium of Eye/*metabolism/radiation effects ; Ultraviolet Rays ; Vitamin A/analogs & derivatives/*metabolism ; *cis-trans-Isomerases
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  • 87
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-01-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Catterall, W A -- New York, N.Y. -- Science. 1989 Jan 13;243(4888):236-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2536189" target="_blank"〉PubMed〈/a〉
    Keywords: Kinetics ; Ligands ; Receptors, Adrenergic, alpha/*metabolism ; Receptors, Adrenergic, beta/*metabolism ; Thermodynamics
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  • 88
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-10
    Description: Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cha, Y -- Murray, C J -- Klinman, J P -- New York, N.Y. -- Science. 1989 Mar 10;243(4896):1325-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2646716" target="_blank"〉PubMed〈/a〉
    Keywords: Alcohol Dehydrogenase/*metabolism ; Benzyl Alcohols ; *Hydrogen ; Kinetics ; Mathematics ; Models, Theoretical ; Oxidation-Reduction ; Saccharomyces cerevisiae/enzymology ; Thermodynamics ; Tritium
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  • 89
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1995-11-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ferster, D -- Spruston, N -- New York, N.Y. -- Science. 1995 Nov 3;270(5237):756-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7481761" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials ; Animals ; Auditory Cortex/cytology/physiology ; Brain/cytology/*physiology ; Electric Conductivity ; Hippocampus/cytology/physiology ; Kinetics ; *Models, Neurological ; Nerve Net/*physiology ; Neurons/*physiology ; Neurons, Afferent/physiology ; *Synaptic Transmission ; Visual Cortex/cytology/physiology
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 90
    Publication Date: 1995-07-14
    Description: Copper-substituted cytochrome c (CuCc) has been used as a structurally faithful, redoxinert inhibitor to probe the mechanism of electron transfer (ET) between Cc molecules and cytochrome c peroxidase (CcP). This inhibitor enhances photoinduced ET quenching of the triplet excited state of a zinc-substituted protein (ZnCcP or ZnCc) by its iron(III) partner (Fe3+Cc or Fe3+CcP). These results show that CcP and Cc form a ternary complex in which one Cc molecule binds tightly at a surface domain of CcP having low ET reactivity, whereas the second Cc molecule binds weakly to the 1:1 complex at a second domain with markedly greater (approximately 10(3)) reactivity. These results also rule out the possibility that Cc bound at the second domain cooperatively enhances ET to Cc at the first domain. The multiphasic kinetics observed for the photoproduced ET intermediate do not reflect electron self-exchange between two Cc molecules within the ternary complex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhou, J S -- Nocek, J M -- DeVan, M L -- Hoffman, B M -- HL13531/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1995 Jul 14;269(5221):204-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7618081" target="_blank"〉PubMed〈/a〉
    Keywords: Cytochrome c Group/chemistry/*metabolism ; Cytochrome-c Peroxidase/chemistry/*metabolism ; *Cytochromes c ; *Electron Transport ; Ferric Compounds/metabolism ; Ferrous Compounds/metabolism ; Hydrogen-Ion Concentration ; Kinetics ; Light ; Models, Chemical ; Oxidation-Reduction ; Zinc/metabolism
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  • 91
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1995-01-20
    Description: In gene regulatory systems in which proteins bind to multiple sites on a DNA molecule, the characterization of chemical mechanisms and single-step reaction rates is difficult because many chemical species may exist simultaneously in a molecular ensemble. This problem was circumvented by detecting DNA looping by the lactose repressor protein of Escherichia coli in single DNA molecules. The looping was detected by monitoring the nanometer-scale Brownian motion of microscopic particles linked to the ends of individual DNA molecules. This allowed the determination of the rates of formation and breakdown of a protein-mediated DNA loop in vitro. The measurements reveal that mechanical strain stored in the loop does not substantially accelerate loop breakdown, and the measurements also show that subunit dissociation of tetrameric repressor is not the predominant loop breakdown pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finzi, L -- Gelles, J -- New York, N.Y. -- Science. 1995 Jan 20;267(5196):378-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7824935" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Biotin ; DNA/chemistry/*metabolism ; Digoxigenin ; Isopropyl Thiogalactoside/pharmacology ; Kinetics ; Molecular Sequence Data ; *Nucleic Acid Conformation ; Repressor Proteins/*metabolism ; Thermodynamics
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  • 92
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1995-04-07
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fisher, R J -- Fivash, M -- New York, N.Y. -- Science. 1995 Apr 7;268(5207):115-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7701331" target="_blank"〉PubMed〈/a〉
    Keywords: Histocompatibility Antigens Class I/*immunology ; Kinetics ; *Models, Immunological ; Protein Binding/immunology ; Receptors, Antigen, T-Cell/*immunology
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  • 93
    Publication Date: 1995-09-29
    Description: The oxidation of toluene by permanganate has been studied as a model for the oxidation of C-H bonds by metal reagents, metalloenzymes, and metal oxide surfaces. In water, the reaction proceeds by hydride (H-) transfer from toluene to a permanganate oxygen, whereas in toluene solution, permanganate abstracts a hydrogen atom (H.). The ability of permanganate to abstract a hydrogen atom is rationalized on the basis of the strong O-H bond formed on H. addition to permanganate. This approach allows understanding and prediction of the rates of hydrogen atom transfer from substrates to metal active sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gardner, K A -- Mayer, J M -- New York, N.Y. -- Science. 1995 Sep 29;269(5232):1849-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Washington, Seattle 98195-1700, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7569922" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon/*chemistry ; Hydrogen/*chemistry ; Kinetics ; Oxidation-Reduction ; Potassium Permanganate/*chemistry ; Solvents ; Spectrophotometry, Ultraviolet ; Thermodynamics ; Toluene/*chemistry
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  • 94
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1995-02-24
    Description: Adenosine diphosphate-ribosylation factor 6 (ARF6), ARF6 mutants, and ARF1 were transiently expressed in Chinese hamster ovary cells, and the effects on receptor-mediated endocytosis were assessed. Overexpressed ARF6 localized to the cell periphery and led to a redistribution of transferrin receptors to the cell surface and a decrease in the rate of uptake of transferrin. Similar results were obtained when a mutant defective in guanosine triphosphate hydrolysis was expressed. Expression of a dominant negative mutant, ARF6(T27N), resulted in an intracellular distribution of transferrin receptors and an inhibition of transferrin recycling to the cell surface. In contrast, overexpression of ARF1 had little or no effect on these parameters of endocytosis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉D'Souza-Schorey, C -- Li, G -- Colombo, M I -- Stahl, P D -- New York, N.Y. -- Science. 1995 Feb 24;267(5201):1175-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7855600" target="_blank"〉PubMed〈/a〉
    Keywords: ADP-Ribosylation Factor 1 ; ADP-Ribosylation Factors ; Amino Acid Sequence ; Animals ; Base Sequence ; CHO Cells ; Cell Membrane/metabolism ; Cricetinae ; *Endocytosis ; GTP-Binding Proteins/analysis/genetics/*physiology ; Golgi Apparatus/metabolism/ultrastructure ; Kinetics ; Molecular Sequence Data ; Mutation ; Receptors, Transferrin/metabolism ; Transferrin/metabolism
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  • 95
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1995-12-15
    Description: For almost 200 years inert antigens have been used for initiating the process of immunization. A procedure is now described in which the antigen used is so highly reactive that a chemical reaction occurs in the antibody combining site during immunization. An organophosphorus diester hapten was used to illustrate this concept coined "reactive immunization." The organophosphonate recruited chemical potential from the immune response that resembled the way these compounds recruit the catalytic power of the serine hydrolases. During this recruitment, a large proportion of the isolated antibodies catalyzed the formation and cleavage of phosphonylated intermediates and subsequent ester hydrolysis. Reactive immunization can augment traditional immunization and enhance the scope of catalytic antibody chemistry. Among the compounds anticipated to be effective are those that contain appropriate reactive functionalities or those that are latently reactive, as in the mechanism-based inhibitors of enzymes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wirsching, P -- Ashley, J A -- Lo, C H -- Janda, K D -- Lerner, R A -- DA08590/DA/NIDA NIH HHS/ -- GM48351/GM/NIGMS NIH HHS/ -- P01 CA27489-16/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1995 Dec 15;270(5243):1775-82.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Scripps Research Institute, Department of Molecular Biology, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8525366" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Catalytic/*chemistry/immunology ; Antibodies, Monoclonal/chemistry/immunology ; Antigen-Antibody Reactions ; Antigens/*chemistry/immunology ; Binding Sites ; Catalysis ; Cattle ; Esters/chemistry/immunology ; Haptens/chemistry/immunology ; Immunization/*methods ; Kinetics ; Mice ; Organophosphonates/chemistry/*immunology ; Thermodynamics ; Tumor Cells, Cultured
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  • 96
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1995-04-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Heinrichs, C -- Munson, P J -- Counts, D R -- Cutler, G B Jr -- Baron, J -- New York, N.Y. -- Science. 1995 Apr 21;268(5209):442-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7716552" target="_blank"〉PubMed〈/a〉
    Keywords: Body Height ; Body Weight ; Cephalometry ; Female ; *Growth ; Humans ; Infant ; Kinetics ; Male ; Regression Analysis
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  • 97
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1996-04-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Joyce, G F -- Dai, X -- De Mesmaeker, A -- New York, N.Y. -- Science. 1996 Apr 5;272(5258):18-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8600526" target="_blank"〉PubMed〈/a〉
    Keywords: Amides/*metabolism ; Kinetics ; RNA, Catalytic/*metabolism ; Ribonucleosides/metabolism
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  • 98
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1996-03-08
    Description: Domain 5 is an essential active-site component of group II intron ribozymes. The role of backbone substituents in D5 function was explored through synthesis of a series of derivatives containing deoxynucleotides at each position along the D5 strand. Kinetic screens revealed that eight 2'-hydroxyl groups were likely to be critical for activity of D5. Through two separate methods, including competitive inhibition and direct kinetic analysis, effects on binding and chemistry were distinguished. Depending on their function, important 2'-hydroxyl groups lie on opposite faces of the molecule, defining distinct loci for molecular recognition and catalysis by D5.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abramovitz, D L -- Friedman, R A -- Pyle, A M -- GM41371/GM/NIGMS NIH HHS/ -- GM50313/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1996 Mar 8;271(5254):1410-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8596912" target="_blank"〉PubMed〈/a〉
    Keywords: Base Composition ; Base Sequence ; Binding Sites ; Catalysis ; Exons ; Hydrogen Bonding ; Hydroxyl Radical/chemistry ; *Introns ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; Oligoribonucleotides/chemistry/metabolism ; RNA/metabolism ; RNA, Catalytic/chemistry/*metabolism
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  • 99
    Publication Date: 1996-11-15
    Description: An approach is described to monitor directly at the level of individual residues the formation of structure during protein folding. A two-dimensional heteronuclear nuclear magnetic resonance (NMR) spectrum was recorded after the rapid initiation of the refolding of a protein labeled with nitrogen-15. The intensities and line shapes of the cross peaks in the spectrum reflected the kinetic time course of the folding events that occurred during the spectral accumulation. The method was used to demonstrate the cooperative nature of the acquisition of the native main chain fold of apo bovine alpha-lactalbumin. The general approach, however, should be applicable to the investigation of a wide range of chemical reactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Balbach, J -- Forge, V -- Lau, W S -- van Nuland, N A -- Brew, K -- Dobson, C M -- New York, N.Y. -- Science. 1996 Nov 15;274(5290):1161-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Oxford Centre for Molecular Sciences, New Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QT, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8895458" target="_blank"〉PubMed〈/a〉
    Keywords: Circular Dichroism ; Fourier Analysis ; Hydrogen-Ion Concentration ; Kinetics ; Lactalbumin/*chemistry ; *Magnetic Resonance Spectroscopy ; Nitrogen Isotopes ; *Protein Folding ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Spectrometry, Fluorescence
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  • 100
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1996-10-25
    Description: Human leukocyte antigen (HLA)-DM is a critical participant in antigen presentation that catalyzes the release of class II-associated invariant chain-derived peptides (CLIP) from newly synthesized class II histocompatibility molecules, freeing the peptide-binding site for acquisition of antigenic peptides. The mechanism for the selective release of CLIP but not other peptides is unknown. DM was found to enhance the rate of peptide dissociation to an extent directly proportional to the intrinsic rate of peptide dissociation from HLA-DR, regardless of peptide sequence. Thus, CLIP is rapidly released in the presence of DM, because its intrinsic rate of dissociation is relatively high. In antigen presentation, DM has the potential to markedly enhance the rate of peptide exchange, favoring the presentation of peptides with slower intrinsic rates of dissociation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Weber, D A -- Evavold, B D -- Jensen, P E -- AI30554/AI/NIAID NIH HHS/ -- AI33614/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1996 Oct 25;274(5287):618-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8849454" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antigen Presentation ; Antigens, Differentiation, B-Lymphocyte/*metabolism ; Binding Sites ; HLA-D Antigens/*metabolism ; HLA-DR Antigens/immunology/*metabolism ; Histocompatibility Antigens Class II/*metabolism ; Humans ; Kinetics ; Molecular Sequence Data ; Peptides/immunology/*metabolism ; Recombinant Fusion Proteins/metabolism
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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