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  • Amino Acid Sequence  (4)
  • Cell & Developmental Biology  (3)
  • Organic Chemistry
  • 1990-1994  (8)
  • 1935-1939
  • 1994  (5)
  • 1992  (3)
  • 1
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    Atomic structure of the cubic core of the pyruvate dehydrogenase multienzyme complex (1992)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1992-03-20
    Description: The highly symmetric pyruvate dehydrogenase multienzyme complexes have molecular masses ranging from 5 to 10 million daltons. They consist of numerous copies of three different enzymes: pyruvate dehydrogenase, dihydrolipoyl transacetylase, and lipoamide dehydrogenase. The three-dimensional crystal structure of the catalytic domain of Azotobacter vinelandii dihydrolipoyl transacetylase has been determined at 2.6 angstrom (A) resolution. Eight trimers assemble as a hollow truncated cube with an edge of 125 A, forming the core of the multienzyme complex. Coenzyme A must enter the 29 A long active site channel from the inside of the cube, and lipoamide must enter from the outside. The trimer of the catalytic domain of dihydrolipoyl transacetylase has a topology identical to chloramphenicol acetyl transferase. The atomic structure of the 24-subunit cube core provides a framework for understanding all pyruvate dehydrogenase and related multienzyme complexes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mattevi, A -- Obmolova, G -- Schulze, E -- Kalk, K H -- Westphal, A H -- de Kok, A -- Hol, W G -- New York, N.Y. -- Science. 1992 Mar 20;255(5051):1544-50.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Groningen, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1549782" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Azotobacter vinelandii/enzymology ; Chloramphenicol O-Acetyltransferase/genetics ; Humans ; Models, Molecular ; Molecular Sequence Data ; Molecular Structure ; Pyruvate Dehydrogenase Complex/*chemistry/genetics ; Sequence Homology, Nucleic Acid
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
    Electronic Resource
    Electronic Resource
    Marsupial fertilization: Some further ultrastructural observations on the dasyurid Sminthopsis Crassicaudata (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 277-292 
    Details
    ISSN: 1040-452X
    Keywords: Oocyte maturation ; Sperm - egg interaction ; Sperm incorporation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Various morphological aspects of in vivo egg maturation and sperm - egg interaction were investigated in the Australian marsupial Sminthopsis crassicaudata with the transmission and scanning electron microscopes. Cortical granules invariably occurred in primary oocytes, with the number increasing after resumption of the first meiotic division. They generally occurred close to the oolemma, including the region near the oocyte nucleus. After mating, spermatozoa with intact acrosomes, which had a homogeneous electron-dense matrix, were found on the outer zona surface, but loss of acrosomal contents had occurred by the time of zona penetration. Sperm incorporation into the egg took place at the metaphase II stage of meiosis, and, at this time, cortical granules disappeared from the egg cortex. Sperm heads with condensed chromatin in the egg cytoplasm had an electron-dense layer of subacrosomal material over part of the dorsal nuclear surface, but no membranes were present around these incorporated spermatozoa. Sperm chromatin decondensation resulted in an elevation of egg cytoplasm, and the cell membrane over this area lacked microvilli. The pronuclear envelope was not laid down until after chromatin decondensation had occurred. By this time the fertilized egg had reached the uterus, and a smooth, electron-dense, shell membrane had been deposited. These observations, together with our previous findings, indicate that some of the processes of sperm - egg interaction are similar to those in eutherian mammals, whereas others appear highly divergent.
    Additional Material: 47 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080320314
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  • 3
    Electronic Resource
    Electronic Resource
    Unusual nuclear structure of the spermatozoon in a marsupial, Sminthopsis crassicaudata (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 37 (1994), S. 78-86 
    Details
    ISSN: 1040-452X
    Keywords: Marsupial ; Sperm head ; Chromatin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The organization of sperm chromatin in the dasyurid marsupial, Sminthopsis crassicaudata, was investigated using various morphological techniques. Transmission electron microscopy indicates two quite distinct chromatin regions became evident late in spermiogenesis with an outer globular region containing blocks of very electron-dense chromatin. Fluorescent light microscopical studies after staining with DNA dyes and 7-amino actinomycin D of testicular, caput, and cauda epididymal spermatozoa showed that this region fluoresced less brightly than the rest of the nucleus, indicating the presence of fewer DNA binding sites. Freeze fracture showed that the chromatin in most of the nucleus had randomly arranged particles of various sizes, but that of the outer region was composed entirely of small particles. This outer region was more resistant to low concentrations of the ionic detergent, SDS, whereas both guanidine hydrochloride and urea together with sodium chloride generally dispersed all the chromatin except that in the outer globular region and in a localized area of the nucleus beneath the acrosome. This study has thus revealed that the outer globular chromatin of these spermatozoa responds differently to ionic detergents and protein denaturing agents and has a different chromatin organization than most of the rest of the nucleus. The significance of these differences remains, however, to be determined. © 1994 Wiley-Liss, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080370111
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  • 4
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    Sensing starvation: a homoserine lactone--dependent signaling pathway in Escherichia coli (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1994-07-22
    Description: When nutrients become limiting, many bacteria differentiate and become resistant to environmental stresses. For Escherichia coli, this process is mediated by the sigma s subunit of RNA polymerase. Expression of sigma s was induced by homoserine lactone, a metabolite synthesized from intermediates in threonine biosynthesis. Homoserine lactone-dependent synthesis of sigma s was prevented by overexpression of a newly identified protein, RspA. The function of homoserine lactone derivatives in many cell density-dependent phenomena and the similarity of RspA to a Streptomyces ambofaciens protein suggest that synthesis of homoserine lactone may be a general signal of starvation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huisman, G W -- Kolter, R -- New York, N.Y. -- Science. 1994 Jul 22;265(5171):537-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7545940" target="_blank"〉PubMed〈/a〉
    Keywords: 4-Butyrolactone/*analogs & derivatives/metabolism/pharmacology ; Amino Acid Sequence ; Bacterial Proteins/*biosynthesis/chemistry/genetics/metabolism ; Catalase/metabolism ; Escherichia coli/genetics/*metabolism ; Gene Expression Regulation, Bacterial ; Models, Biological ; Molecular Sequence Data ; Operon ; Phenotype ; Sigma Factor/*biosynthesis/genetics ; *Signal Transduction ; Transcription, Genetic ; Vibrio/genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Crystal structure of a catalytic antibody with a serine protease active site (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1994-08-19
    Description: The three-dimensional structure of an unusually active hydrolytic antibody with a phosphonate transition state analog (hapten) bound to the active site has been solved to 2.5 A resolution. The antibody (17E8) catalyzes the hydrolysis of norleucine and methionine phenyl esters and is selective for amino acid esters that have the natural alpha-carbon L configuration. A plot of the pH-dependence of the antibody-catalyzed reaction is bell-shaped with an activity maximum at pH 9.5; experiments on mechanism lend support to the formation of a covalent acyl-antibody intermediate. The structural and kinetic data are complementary and support a hydrolytic mechanism for the antibody that is remarkably similar to that of the serine proteases. The antibody active site contains a Ser-His dyad structure proximal to the phosphorous atom of the bound hapten that resembles two of the three components of the Ser-His-Asp catalytic triad of serine proteases. The antibody active site also contains a Lys residue to stabilize oxyanion formation, and a hydrophobic binding pocket for specific substrate recognition of norleucine and methionine side chains. The structure identifies active site residues that mediate catalysis and suggests specific mutations that may improve the catalytic efficiency of the antibody. This high resolution structure of a catalytic antibody-hapten complex shows that antibodies can converge on active site structures that have arisen through natural enzyme evolution.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhou, G W -- Guo, J -- Huang, W -- Fletterick, R J -- Scanlan, T S -- DK39304/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1994 Aug 19;265(5175):1059-64.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8066444" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antibodies, Catalytic/*chemistry/immunology/metabolism ; Binding Sites ; Computer Graphics ; Crystallization ; Crystallography, X-Ray ; Haptens/metabolism ; Hydrogen Bonding ; Hydrogen-Ion Concentration ; Hydrolysis ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Serine Endopeptidases/*chemistry/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 6
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    An all D-amino acid opioid peptide with central analgesic activity from a combinatorial library (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1994-12-23
    Description: A synthetic combinatorial library containing 52,128,400 D-amino acid hexapeptides was used to identify a ligand for the mu opioid receptor. The peptide, Ac-rfwink-NH2, bears no resemblance to any known opioid peptide. Simulations using molecular dynamics, however, showed that three amino acid moieties have the same spatial orientation as the corresponding pharmacophoric groups of the opioid peptide PLO17. Ac-rfwink-NH2 was shown to be a potent agonist at the mu receptor and induced long-lasting analgesia in mice. Analgesia produced by intraperitoneally administered Ac-rfwink-NH2 was blocked by intracerebroventricular administration of naloxone, demonstrating that this peptide may cross the blood-brain barrier.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dooley, C T -- Chung, N N -- Wilkes, B C -- Schiller, P W -- Bidlack, J M -- Pasternak, G W -- Houghten, R A -- DA-000138/DA/NIDA NIH HHS/ -- DA-02615/DA/NIDA NIH HHS/ -- DA-03742/DA/NIDA NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Dec 23;266(5193):2019-22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Torrey Pines Institute for Molecular Studies, San Diego, CA 92121.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7801131" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Analgesics/chemistry/metabolism/*pharmacology ; Animals ; Brain/metabolism ; Dose-Response Relationship, Drug ; Endorphins/pharmacology ; Enkephalin, Ala(2)-MePhe(4)-Gly(5)- ; Enkephalin, D-Penicillamine (2,5)- ; Enkephalins/metabolism ; Guinea Pigs ; Injections, Intraventricular ; Male ; Mice ; Models, Molecular ; Molecular Sequence Data ; Naloxone/administration & dosage/pharmacology ; Opioid Peptides/chemistry/metabolism/*pharmacology ; Pain Measurement ; Protein Conformation ; Rats ; Receptors, Opioid, mu/agonists/metabolism ; Stereoisomerism
    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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  • 7
    Electronic Resource
    Electronic Resource
    Tetrazolverbindungen. 7. Neuartig verknüpfte Pyrazolyl- und Isoxazolyl-tetrazole aus Enaminoketon-Vorstufen (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 79-82 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 7. New Types of Pyrazolyl- and Isoxazolyl-tetrazoles from Enamino Ketone Precursors
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360118
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  • 8
    Electronic Resource
    Electronic Resource
    Enhanced in vitro growth of murine fibroblast cells and preimplantation embryos cultured in medium supplemented with an amphipathic peptide (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 106-113 
    Details
    ISSN: 1040-452X
    Keywords: Embryo development ; Lytic peptide ; Growth factor ; Cecropin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Preliminary studies on the proliferative effects of lytic peptides were carried out using NIH 3T3 murine fibroblast cells and human lymphocytes. Cells were cultured in various concentrations of three different amphipathic peptides (SB-37, Shiva-1, and Vishnu), and enhanced proliferation was determined by uptake of 3Hthymidine with treated cells compared with control cultures. Enhanced proliferation of 3T3 cells was observed in cultures containing 50 μM or less SB-37. The primary study consisted of 263 four-cell- to eight-cell-stage mouse embryos from naturally bred mice and incubated in Whitten's medium containing 0.2, 1, or 10 μM of the amino terminus of an amphipathic cecropin B analog (Vishnu) or in Whitten's medium alone. Embryos were cultured to the hatched blastocyst stage, and effect of treatment was determined by the rate of growth to that stage of development. Statistical analysis revealed that culture in all three levels of Vishnu significantly accelerated in vitro growth of these stages of preimplantation embryos compared with controls. These results indicate that Vishnu promotes increased cleavage rates of embryos in vitro. A growth factor receptor clustering mechanism of action is proposed. This peptide may have some potential as an embryo culture medium additive to enhance in vitro growth rate.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080310204
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