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  • Kinetics
  • American Association for the Advancement of Science (AAAS)  (33)
  • American Institute of Physics (AIP)
  • Oxford University Press
  • 2020-2022
  • 1985-1989  (33)
  • 1989  (33)
Collection
Publisher
  • American Association for the Advancement of Science (AAAS)  (33)
  • American Institute of Physics (AIP)
  • Oxford University Press
  • Springer  (6)
Years
  • 2020-2022
  • 1985-1989  (33)
Year
  • 1
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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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  • 2
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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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  • 3
    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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  • 4
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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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  • 5
    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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  • 6
    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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  • 7
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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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  • 8
    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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  • 9
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    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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  • 10
    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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  • 11
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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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  • 12
    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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  • 13
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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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  • 14
    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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  • 15
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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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  • 16
    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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  • 17
    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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  • 18
    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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  • 19
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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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  • 20
    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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  • 21
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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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  • 22
    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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  • 23
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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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  • 24
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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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  • 25
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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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  • 26
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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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  • 27
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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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  • 28
    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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  • 29
    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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  • 30
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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
    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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  • 31
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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
    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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  • 32
    Publication Date: 1989-09-01
    Description: Human alpha- and beta-globin genes were separately fused downstream of two erythroid-specific deoxyribonuclease (DNase) I super-hypersensitive sites that are normally located 50 kilobases upstream of the human beta-globin gene. These two constructs were coinjected into fertilized mouse eggs, and expression was analyzed in transgenic animals that developed. Mice that had intact copies of the transgenes expressed high levels of correctly initiated human alpha- and beta-globin messenger RNA specifically in erythroid tissue. An authentic human hemoglobin was formed in adult erythrocytes that when purified had an oxygen equilibrium curve identical to the curve of native human hemoglobin A (Hb A). Thus, functional human hemoglobin can be synthesized in transgenic mice. This provides a foundation for production of mouse models of human hemoglobinopathies such as sickle cell disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Behringer, R R -- Ryan, T M -- Reilly, M P -- Asakura, T -- Palmiter, R D -- Brinster, R L -- Townes, T M -- HD-09172/HD/NICHD NIH HHS/ -- HL-35559/HL/NHLBI NIH HHS/ -- HL-38632/HL/NHLBI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1989 Sep 1;245(4921):971-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Reproductive Physiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2772649" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Deoxyribonuclease I ; Female ; *Genes ; Globins/biosynthesis/*genetics ; Hemoglobins/biosynthesis/*genetics ; Humans ; Kinetics ; Mice ; Mice, Transgenic ; Oxyhemoglobins/metabolism ; RNA, Messenger/genetics ; Transcription, Genetic
    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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  • 33
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-30
    Description: High-resolution differential interference contrast microscopy and digital imaging of the fluorescent calcium indicator dye fura-2 were performed simultaneously in single rat salivary gland acinar cells to examine the effects of muscarinic stimulation on cell volume and cytoplasmic calcium concentration ([Ca2+]i). Agonist stimulation of fluid secretion is initially associated with a rapid tenfold increase in [Ca2+]i as well as a substantial cell shrinkage. Subsequent changes of cell volume in the continued presence of agonist are tightly coupled to dynamic levels of [Ca2+]i, even during [Ca2+]i oscillations. Experiments with Ca2+ chelators and ionophores showed that physiological elevations of [Ca2+]i are necessary and sufficient to cause changes in cell volume. The relation between [Ca2+]i and cell volume suggests that the latter reflects the secretory state of the acinar cell. Agonist-induced changes in [Ca2+]i, by modulating specific ion permeabilities, result in solute movement into or out of the cell. The resultant cell volume changes may be important in modulating salivary secretion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Foskett, J K -- Melvin, J E -- New York, N.Y. -- Science. 1989 Jun 30;244(4912):1582-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physiology Department, Armed Forces Radiobiology Research Institute, Bethesda, MD 20814.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2500708" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Benzofurans ; Calcium/*metabolism ; Carbachol/pharmacology ; Cell Membrane/physiology ; Chelating Agents ; Chlorides/metabolism ; Cytoplasm/metabolism ; Egtazic Acid/analogs & derivatives ; Ethers/pharmacology ; Fluorescent Dyes ; Fura-2 ; Ionomycin ; Ionophores ; Kinetics ; Potassium/metabolism ; Rats ; Saliva/*secretion ; Salivary Glands/*cytology/drug effects/physiology
    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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