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  • Articles  (244)
  • Computational Chemistry and Molecular Modeling  (134)
  • Binding Sites  (110)
  • 1995-1999  (61)
  • 1990-1994  (183)
  • 1950-1954
  • 1915-1919
  • 1997  (61)
  • 1990  (183)
  • 1917
  • Computer Science  (244)
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  • Articles  (244)
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  • 1995-1999  (61)
  • 1990-1994  (183)
  • 1950-1954
  • 1915-1919
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  • 1
    Publication Date: 1997-12-31
    Description: The nuclear factor of activated T cells (NFAT) group of transcription factors is retained in the cytoplasm of quiescent cells. NFAT activation is mediated in part by induced nuclear import. This process requires calcium-dependent dephosphorylation of NFAT caused by the phosphatase calcineurin. The c-Jun amino-terminal kinase (JNK) phosphorylates NFAT4 on two sites. Mutational removal of the JNK phosphorylation sites caused constitutive nuclear localization of NFAT4. In contrast, JNK activation in calcineurin-stimulated cells caused nuclear exclusion of NFAT4. These findings show that the nuclear accumulation of NFAT4 promoted by calcineurin is opposed by the JNK signal transduction pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chow, C W -- Rincon, M -- Cavanagh, J -- Dickens, M -- Davis, R J -- CA58396/CA/NCI NIH HHS/ -- CA65831/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1997 Nov 28;278(5343):1638-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9374467" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; COS Cells ; Calcineurin/metabolism ; Calcineurin Inhibitors ; Calcium-Calmodulin-Dependent Protein Kinases/*metabolism ; Cell Line ; Cell Nucleus/*metabolism ; Cyclosporine/pharmacology ; Cytoplasm/metabolism ; DNA-Binding Proteins/genetics/*metabolism ; Humans ; JNK Mitogen-Activated Protein Kinases ; Jurkat Cells ; Mitogen-Activated Protein Kinase Kinases ; *Mitogen-Activated Protein Kinases ; Mutation ; NFATC Transcription Factors ; *Nuclear Proteins ; Phosphorylation ; Protein Kinases/metabolism ; Recombinant Fusion Proteins/metabolism ; *Signal Transduction ; T-Lymphocytes/metabolism ; Transcription Factors/genetics/*metabolism ; Transcription, Genetic
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  • 2
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-05-23
    Description: During translation errors of aminoacylation are corrected in editing reactions which ensure that an amino acid is stably attached to its corresponding transfer RNA (tRNA). Previous studies have not shown whether the tRNA nucleotides needed for effecting translational editing are the same as or distinct from those required for aminoacylation, but several considerations have suggested that they are the same. Here, designed tRNAs that are highly active for aminoacylation but are not active in translational editing are presented. The editing reaction can be controlled by manipulation of nucleotides at the corner of the L-shaped tRNA. In contrast, these manipulations do not affect aminoacylation. These results demonstrate the segregation of nucleotide determinants for the editing and aminoacylation functions of tRNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hale, S P -- Auld, D S -- Schmidt, E -- Schimmel, P -- GM15539/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 May 23;276(5316):1250-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9157882" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylation ; Base Sequence ; Binding Sites ; Cloning, Molecular ; Escherichia coli ; Molecular Sequence Data ; Nucleic Acid Conformation ; *RNA Editing ; RNA, Transfer/*metabolism ; RNA, Transfer, Ile/chemistry/metabolism ; RNA, Transfer, Val/chemistry/metabolism
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  • 3
    Publication Date: 1997-04-18
    Description: The crystal structure of the adenine nucleotide exchange factor GrpE in complex with the adenosine triphosphatase (ATPase) domain of Escherichia coli DnaK [heat shock protein 70 (Hsp70)] was determined at 2.8 angstrom resolution. A dimer of GrpE binds asymmetrically to a single molecule of DnaK. The structure of the nucleotide-free ATPase domain in complex with GrpE resembles closely that of the nucleotide-bound mammalian Hsp70 homolog, except for an outward rotation of one of the subdomains of the protein. This conformational change is not consistent with tight nucleotide binding. Two long alpha helices extend away from the GrpE dimer and suggest a role for GrpE in peptide release from DnaK.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Harrison, C J -- Hayer-Hartl, M -- Di Liberto, M -- Hartl, F -- Kuriyan, J -- New York, N.Y. -- Science. 1997 Apr 18;276(5311):431-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratories of Molecular Biophysics and Howard Hughes Medical Institute, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9103205" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Diphosphate/metabolism ; Adenosine Triphosphatases/*chemistry/metabolism ; Amino Acid Sequence ; Bacterial Proteins/*chemistry/metabolism ; Binding Sites ; Crystallography, X-Ray ; Dimerization ; *Escherichia coli Proteins ; HSP70 Heat-Shock Proteins/*chemistry/metabolism ; Heat-Shock Proteins/*chemistry/metabolism ; Hydrogen Bonding ; Models, Molecular ; Molecular Chaperones/*chemistry/metabolism ; Molecular Sequence Data ; *Protein Conformation ; Protein Structure, Secondary
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  • 4
    Publication Date: 1997-11-21
    Description: Many neuropeptides and peptide hormones require amidation at the carboxyl terminus for activity. Peptidylglycine alpha-amidating monooxygenase (PAM) catalyzes the amidation of these diverse physiological regulators. The amino-terminal domain of the bifunctional PAM protein is a peptidylglycine alpha-hydroxylating monooxygenase (PHM) with two coppers that cycle through cupric and cuprous oxidation states. The anomalous signal of the endogenous coppers was used to determine the structure of the catalytic core of oxidized rat PHM with and without bound peptide substrate. These structures strongly suggest that the PHM reaction proceeds via activation of substrate by a copper-bound oxygen species. The mechanistic and structural insight gained from the PHM structures can be directly extended to dopamine beta-monooxygenase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prigge, S T -- Kolhekar, A S -- Eipper, B A -- Mains, R E -- Amzel, L M -- DK32949/DK/NIDDK NIH HHS/ -- GM44692/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Nov 14;278(5341):1300-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9360928" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Catalysis ; Copper/chemistry/metabolism ; Crystallography, X-Ray ; Dipeptides/metabolism ; Dopamine beta-Hydroxylase/chemistry/metabolism ; Electrons ; Hydroxylation ; Ligands ; Mixed Function Oxygenases/*chemistry/metabolism ; Models, Molecular ; *Multienzyme Complexes ; Oxidation-Reduction ; Oxygen/metabolism ; Peptides/metabolism ; *Protein Conformation ; Protein Structure, Secondary ; Rats
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  • 5
    Publication Date: 1997-07-18
    Description: A genetic block was introduced in the first condensation step of the polyketide biosynthetic pathway that leads to the formation of 6-deoxyerythronolide B (6-dEB), the macrocyclic precursor of erythromycin. Exogenous addition of designed synthetic molecules to small-scale cultures of this null mutant resulted in highly selective multimilligram production of unnatural polyketides, including aromatic and ring-expanded variants of 6-dEB. Unexpected incorporation patterns were observed, illustrating the catalytic versatility of modular polyketide synthases. Further processing of some of these scaffolds by postpolyketide enzymes of the erythromycin pathway resulted in the generation of novel antibacterials with in vitro potency comparable to that of their natural counterparts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jacobsen, J R -- Hutchinson, C R -- Cane, D E -- Khosla, C -- CA66736/CA/NCI NIH HHS/ -- GM22172/GM/NIGMS NIH HHS/ -- GM31925/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1997 Jul 18;277(5324):367-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical Engineering, Stanford University, Stanford, CA 94305-5025, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9219693" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Substitution ; Bacillus cereus/drug effects/growth & development ; Binding Sites ; Catalysis ; Cyclization ; Erythromycin/*analogs & derivatives/biosynthesis/pharmacology ; Microbial Sensitivity Tests ; Multienzyme Complexes/*genetics/*metabolism ; *Mutagenesis, Site-Directed ; Saccharopolyspora/genetics/metabolism ; Streptomyces/enzymology/genetics/*metabolism ; Transformation, Genetic
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  • 6
    Publication Date: 1997-02-28
    Description: The small guanosine triphosphatase (GTPase) Rho is implicated in the formation of stress fibers and focal adhesions in fibroblasts stimulated by extracellular signals such as lysophosphatidic acid (LPA). Rho-kinase is activated by Rho and may mediate some biological effects of Rho. Microinjection of the catalytic domain of Rho-kinase into serum-starved Swiss 3T3 cells induced the formation of stress fibers and focal adhesions, whereas microinjection of the inactive catalytic domain, the Rho-binding domain, or the pleckstrin-homology domain inhibited the LPA-induced formation of stress fibers and focal adhesions. Thus, Rho-kinase appears to mediate signals from Rho and to induce the formation of stress fibers and focal adhesions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Amano, M -- Chihara, K -- Kimura, K -- Fukata, Y -- Nakamura, N -- Matsuura, Y -- Kaibuchi, K -- New York, N.Y. -- Science. 1997 Feb 28;275(5304):1308-11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Signal Transduction, Nara Institute of Science and Technology, Ikoma 630-01, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9036856" target="_blank"〉PubMed〈/a〉
    Keywords: 3T3 Cells ; Actins/*metabolism ; Adenosine Triphosphate/metabolism ; Animals ; Binding Sites ; *Cell Adhesion ; Cell Line ; DNA, Complementary/genetics ; Enzyme Inhibitors/pharmacology ; GTP Phosphohydrolases/metabolism ; Intracellular Signaling Peptides and Proteins ; Lysophospholipids/pharmacology ; Mice ; Mutation ; Protein-Serine-Threonine Kinases/antagonists & inhibitors/genetics/*metabolism ; Recombinant Fusion Proteins/metabolism ; Staurosporine/pharmacology ; rho-Associated Kinases
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-07-04
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roush, W -- New York, N.Y. -- Science. 1997 Jul 4;277(5322):31-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9229767" target="_blank"〉PubMed〈/a〉
    Keywords: Alzheimer Disease/metabolism/*pathology ; Amyloid beta-Peptides/immunology ; Antibodies/immunology ; Binding Sites ; Brain/*pathology ; Brain Chemistry ; Humans ; Phosphates/metabolism ; tau Proteins/immunology/metabolism
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  • 8
    Publication Date: 1997-06-13
    Description: The crystal structures of a germline antibody Fab fragment and its complex with hapten have been solved at 2.1 A resolution. These structures are compared with the corresponding crystal structures of the affinity-matured antibody, 48G7, which has a 30,000 times higher affinity for hapten as a result of nine replacement somatic mutations. Significant changes in the configuration of the combining site occur upon binding of hapten to the germline antibody, whereas hapten binds to the mature antibody by a lock-and-key fit mechanism. The reorganization of the combining site that was nucleated by hapten binding is further optimized by somatic mutations that occur up to 15 from bound hapten. These results suggest that the binding potential of the primary antibody repertoire may be significantly expanded by the ability of germline antibodies to adopt more than one combining-site configuration, with both antigen binding and somatic mutation stabilizing the configuration with optimal hapten complementarity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wedemayer, G J -- Patten, P A -- Wang, L H -- Schultz, P G -- Stevens, R C -- R01 AI39089/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1997 Jun 13;276(5319):1665-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley, CA 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9180069" target="_blank"〉PubMed〈/a〉
    Keywords: Antibodies, Catalytic/*chemistry/genetics/immunology ; Antibody Affinity ; Antibody Diversity ; Antigen-Antibody Complex ; Antigen-Antibody Reactions ; Binding Sites ; *Binding Sites, Antibody ; Crystallography, X-Ray ; *Evolution, Molecular ; Haptens/immunology ; Hydrogen Bonding ; Immunoglobulin Fab Fragments/*chemistry/genetics/immunology ; Molecular Sequence Data ; Mutation ; Protein Conformation ; Protein Structure, Secondary
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  • 9
    Publication Date: 1997-06-06
    Description: Apoptosis of Jurkat T cells induced the caspase-mediated proteolytic cleavage of p21-activated kinase 2 (PAK2). Cleavage occurred between the amino-terminal regulatory domain and the carboxyl-terminal catalytic domain, which generated a constitutively active PAK2 fragment. Stable Jurkat cell lines that expressed a dominant-negative PAK mutant were resistant to the Fas-induced formation of apoptotic bodies, but had an enhanced externalization of phosphatidylserine at the cell surface. Thus, proteolytic activation of PAK2 represents a guanosine triphosphatase-independent mechanism of PAK regulation that allows PAK2 to regulate morphological changes that are seen in apoptotic cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rudel, T -- Bokoch, G M -- GM39434/GM/NIGMS NIH HHS/ -- HL48008/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1997 Jun 6;276(5318):1571-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Immunology, 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/9171063" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Chloromethyl Ketones/pharmacology ; *Apoptosis ; Binding Sites ; Caspase 3 ; *Caspases ; Cell Membrane/*metabolism ; Cysteine Endopeptidases/*metabolism ; Cysteine Proteinase Inhibitors/pharmacology ; Enzyme Activation ; Fas Ligand Protein ; Humans ; Jurkat Cells ; Membrane Glycoproteins/metabolism ; Phosphatidylserines/metabolism ; Protein-Serine-Threonine Kinases/*metabolism ; Recombinant Proteins/metabolism ; T-Lymphocytes/*cytology/enzymology ; p21-Activated Kinases
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  • 10
    Publication Date: 1997-08-15
    Description: Catalytic protein subunits of telomerase from the ciliate Euplotes aediculatus and the yeast Saccharomyces cerevisiae contain reverse transcriptase motifs. Here the homologous genes from the fission yeast Schizosaccharomyces pombe and human are identified. Disruption of the S. pombe gene resulted in telomere shortening and senescence, and expression of mRNA from the human gene correlated with telomerase activity in cell lines. Sequence comparisons placed the telomerase proteins in the reverse transcriptase family but revealed hallmarks that distinguish them from retroviral and retrotransposon relatives. Thus, the proposed telomerase catalytic subunits are phylogenetically conserved and represent a deep branch in the evolution of reverse transcriptases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nakamura, T M -- Morin, G B -- Chapman, K B -- Weinrich, S L -- Andrews, W H -- Lingner, J -- Harley, C B -- Cech, T R -- GM28039/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Aug 15;277(5328):955-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9252327" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Catalysis ; Cell Line ; DNA-Binding Proteins ; Evolution, Molecular ; Genes, Fungal ; Humans ; Introns ; Molecular Sequence Data ; Phylogeny ; Proteins/*chemistry/genetics/metabolism ; *Rna ; RNA, Messenger/genetics/metabolism ; RNA-Directed DNA Polymerase/chemistry ; Retroelements ; Schizosaccharomyces/*enzymology/genetics/growth & development ; Schizosaccharomyces pombe Proteins ; Sequence Alignment ; Telomerase/*chemistry/genetics/metabolism ; Telomere/metabolism
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-02-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barinaga, M -- New York, N.Y. -- Science. 1997 Feb 14;275(5302):928.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9053995" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Chromosomes, Fungal/metabolism ; DNA, Fungal/metabolism ; DNA-Binding Proteins/metabolism ; Fungal Proteins/*metabolism ; GTP-Binding Proteins/*metabolism ; Repressor Proteins/metabolism ; Saccharomyces cerevisiae/genetics/*metabolism ; *Saccharomyces cerevisiae Proteins ; Telomerase/*metabolism ; Telomere/*metabolism ; *Telomere-Binding Proteins ; rap GTP-Binding Proteins
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  • 12
    Publication Date: 1997-06-20
    Description: Bactericidal/permeability-increasing protein (BPI), a potent antimicrobial protein of 456 residues, binds to and neutralizes lipopolysaccharides from the outer membrane of Gram-negative bacteria. At a resolution of 2.4 angstroms, the crystal structure of human BPI shows a boomerang-shaped molecule formed by two similar domains. Two apolar pockets on the concave surface of the boomerang each bind a molecule of phosphatidylcholine, primarily by interacting with their acyl chains; this suggests that the pockets may also bind the acyl chains of lipopolysaccharide. As a model for the related plasma lipid transfer proteins, BPI illuminates a mechanism of lipid transfer for this protein family.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Beamer, L J -- Carroll, S F -- Eisenberg, D -- GM31299/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jun 20;276(5320):1861-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉UCLA-DOE Laboratory of Structural Biology and Molecular Medicine, Molecular Biology Institute, 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/9188532" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antimicrobial Cationic Peptides ; Binding Sites ; Blood Bactericidal Activity ; Blood Proteins/*chemistry/metabolism ; Crystallization ; Crystallography, X-Ray ; Humans ; Lipopolysaccharides/metabolism ; *Membrane Proteins ; Models, Molecular ; Molecular Sequence Data ; Phosphatidylcholines/chemistry/*metabolism ; *Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary
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  • 13
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-11-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sacchettini, J C -- Poulter, C D -- New York, N.Y. -- Science. 1997 Sep 19;277(5333):1788-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Texas A & M University, College Station, TX 77843-2128, USA. sacchett@seabass.tamu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9324768" target="_blank"〉PubMed〈/a〉
    Keywords: *Alkyl and Aryl Transferases ; Binding Sites ; Carotenoids/biosynthesis ; Catalysis ; Cyclization ; Geranyltranstransferase ; *Intramolecular Lyases ; *Intramolecular Transferases ; Isomerases/*chemistry/metabolism ; Protein Folding ; Sterols/biosynthesis ; Terpenes/*metabolism ; Transferases/chemistry/metabolism
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  • 14
    Publication Date: 1997-07-04
    Description: On the basis of x-ray diffraction data to a resolution of 2.9 angstroms, atomic models of most protein components of the bovine cytochrome bc1 complex were built, including core 1, core 2, cytochrome b, subunit 6, subunit 7, a carboxyl-terminal fragment of cytochrome c1, and an amino-terminal fragment of the iron-sulfur protein. The positions of the four iron centers within the bc1 complex and the binding sites of the two specific respiratory inhibitors antimycin A and myxothiazol were identified. The membrane-spanning region of each bc1 complex monomer consists of 13 transmembrane helices, eight of which belong to cytochrome b. Closely interacting monomers are arranged as symmetric dimers and form cavities through which the inhibitor binding pockets can be accessed. The proteins core 1 and core 2 are structurally similar to each other and consist of two domains of roughly equal size and identical folding topology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xia, D -- Yu, C A -- Kim, H -- Xia, J Z -- Kachurin, A M -- Zhang, L -- Yu, L -- Deisenhofer, J -- GM 30721/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jul 4;277(5322):60-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9204897" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antimycin A/metabolism/pharmacology ; Binding Sites ; Cattle ; Crystallography, X-Ray ; Cytochrome b Group/chemistry ; Cytochromes c1/chemistry ; Dimerization ; Electron Transport Complex III/*chemistry/metabolism ; Intracellular Membranes/enzymology ; Iron/metabolism ; Methacrylates ; Mitochondria, Heart/*enzymology ; Models, Molecular ; Molecular Sequence Data ; Oxidation-Reduction ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Thiazoles/metabolism/pharmacology
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  • 15
    Publication Date: 1997-01-17
    Description: Transmembrane receptors for hormones, neurotransmitters, light, and odorants mediate their cellular effects by activating heterotrimeric guanine nucleotide-binding proteins (G proteins). Crystal structures have revealed contact surfaces between G protein subunits, but not the surfaces or molecular mechanism through which Galphabetagamma responds to activation by transmembrane receptors. Such a surface was identified from the results of testing 100 mutant alpha subunits of the retinal G protein transducin for their ability to interact with rhodopsin. Sites at which alanine substitutions impaired this interaction mapped to two distinct Galpha surfaces: a betagamma-binding surface and a putative receptor-interacting surface. On the basis of these results a mechanism for receptor-catalyzed exchange of guanosine diphosphate for guanosine triphosphate is proposed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Onrust, R -- Herzmark, P -- Chi, P -- Garcia, P D -- Lichtarge, O -- Kingsley, C -- Bourne, H R -- CA-54427/CA/NCI NIH HHS/ -- GM-27800/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jan 17;275(5298):381-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143-0450, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8994033" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Compounds/pharmacology ; Animals ; Binding Sites ; COS Cells ; Fluorides/pharmacology ; Guanosine 5'-O-(3-Thiotriphosphate)/metabolism ; Guanosine Diphosphate/metabolism ; Models, Molecular ; Mutation ; Phenotype ; *Protein Conformation ; Retinaldehyde/pharmacology ; Rhodopsin/*metabolism/pharmacology ; Rod Cell Outer Segment/metabolism ; Transducin/*chemistry/metabolism
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  • 16
    Publication Date: 1997-07-18
    Description: CD1 represents a third lineage of antigen-presenting molecules that are distantly related to major histocompatibility complex (MHC) molecules in the immune system. The crystal structure of mouse CD1d1, corresponding to human CD1d, at 2.8 resolution shows that CD1 adopts an MHC fold that is more closely related to that of MHC class I than to that of MHC class II. The binding groove, although significantly narrower, is substantially larger because of increased depth and it has only two major pockets that are almost completely hydrophobic. The extreme hydrophobicity and shape of the binding site are consistent with observations that human CD1b and CD1c can present mycobacterial cell wall antigens, such as mycolic acid and lipoarabinomannans. However, mouse CD1d1 can present very hydrophobic peptides, but must do so in a very different way from MHC class Ia and class II molecules.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zeng, Z -- Castano, A R -- Segelke, B W -- Stura, E A -- Peterson, P A -- Wilson, I A -- CA-58896/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1997 Jul 18;277(5324):339-45.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and the Skaggs Institute for Chemical Biology at the Scripps Research Institute, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9219685" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antigen Presentation ; Antigens, CD1/*chemistry/immunology/metabolism ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; Glycolipids/chemistry/immunology/metabolism ; Histocompatibility Antigens Class I/chemistry ; Histocompatibility Antigens Class II/chemistry ; Humans ; Hydrogen Bonding ; Ligands ; Lipid Metabolism ; Lipids/chemistry/immunology ; Mice ; Models, Molecular ; *Protein Conformation ; *Protein Folding ; Protein Structure, Secondary ; Protein Structure, Tertiary ; T-Lymphocyte Subsets/immunology
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  • 17
    Publication Date: 1997-09-26
    Description: A distant relative of catalase that is specialized for metabolism of a fatty acid hydroperoxide was identified. This heme peroxidase occurs in coral as part of a fusion protein, the other component of which is a lipoxygenase that forms the hydroperoxide substrate. The end product is an unstable epoxide (an allene oxide) that is a potential precursor of prostaglandin-like molecules. These results extend the known chemistry of catalase-like proteins and reveal a distinct type of enzymatic construct involved in the metabolism of polyunsaturated fatty acids.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koljak, R -- Boutaud, O -- Shieh, B H -- Samel, N -- Brash, A R -- GM49502/GM/NIGMS NIH HHS/ -- TW00404/TW/FIC NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 26;277(5334):1994-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6602, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9302294" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Arachidonic Acid/metabolism ; Binding Sites ; Catalase/chemistry ; Catalysis ; Cloning, Molecular ; Cnidaria/*enzymology/genetics ; Hydrogen Peroxide/metabolism ; *Intramolecular Oxidoreductases ; Isomerases/chemistry ; Lipoxygenase/*chemistry/genetics/isolation & purification/metabolism ; Molecular Sequence Data ; Peroxidase/*chemistry/genetics/isolation & purification/metabolism ; Peroxidases/*chemistry/isolation & purification/metabolism ; Recombinant Proteins/metabolism ; Sequence Homology, Amino Acid
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  • 18
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-09-20
    Description: Structure determination at 2.4 angstrom resolution shows that lambda-exonuclease consists of three subunits that form a toroid. The central channel is funnel shaped, tapering from an inner diameter of about 30 angstroms at the wider end to 15 angstroms at the narrow end. This is adequate to accommodate the DNA substrate and thus provides a structural basis for the ability of the enzyme to sequentially hydrolyze thousands of nucleotides in a highly processive manner. The results also suggest the locations of the active sites and the constraints that limit cleavage to a single strand.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kovall, R -- Matthews, B W -- GM20066/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 19;277(5333):1824-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Physics, University of Oregon, Eugene, OR 97403, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9295273" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriophage lambda/enzymology ; Binding Sites ; Crystallography, X-Ray ; DNA/genetics/*metabolism ; DNA, Single-Stranded/genetics/*metabolism ; DNA, Viral/genetics/metabolism ; Evolution, Molecular ; Exodeoxyribonucleases/*chemistry/genetics/metabolism ; Hydrolysis ; Magnesium/metabolism ; Models, Molecular ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Recombination, Genetic ; Viral Proteins
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  • 19
    Publication Date: 1997-03-21
    Description: Protein farnesyltransferase (FTase) catalyzes the carboxyl-terminal lipidation of Ras and several other cellular signal transduction proteins. The essential nature of this modification for proper function of these proteins has led to the emergence of FTase as a target for the development of new anticancer therapy. Inhibition of this enzyme suppresses the transformed phenotype in cultured cells and causes tumor regression in animal models. The crystal structure of heterodimeric mammalian FTase was determined at 2.25 angstrom resolution. The structure shows a combination of two unusual domains: a crescent-shaped seven-helical hairpin domain and an alpha-alpha barrel domain. The active site is formed by two clefts that intersect at a bound zinc ion. One cleft contains a nine-residue peptide that may mimic the binding of the Ras substrate; the other cleft is lined with highly conserved aromatic residues appropriate for binding the farnesyl isoprenoid with required specificity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Park, H W -- Boduluri, S R -- Moomaw, J F -- Casey, P J -- Beese, L S -- GM46372/GM/NIGMS NIH HHS/ -- GM52382/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Mar 21;275(5307):1800-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, 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/9065406" target="_blank"〉PubMed〈/a〉
    Keywords: *Alkyl and Aryl Transferases ; Binding Sites ; Crystallography, X-Ray ; Dimerization ; Ligands ; Models, Molecular ; Molecular Sequence Data ; Mutation ; *Protein Conformation ; Protein Structure, Secondary ; Proteins/metabolism ; Sequence Alignment ; Transferases/*chemistry/genetics/metabolism ; Zinc/metabolism
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  • 20
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-04-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barinaga, M -- New York, N.Y. -- Science. 1997 Apr 25;276(5312):528-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9148410" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Catalysis ; DNA-Binding Proteins ; Euplotes/enzymology ; Fungal Proteins/*chemistry/genetics/isolation & purification/metabolism ; Genes, Fungal ; *Rna ; RNA-Directed DNA Polymerase/*chemistry/genetics/isolation & ; purification/metabolism ; Saccharomyces cerevisiae/enzymology/genetics ; Telomerase/*chemistry/genetics/isolation & purification/metabolism
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  • 21
    Publication Date: 1997-07-18
    Description: The three-dimensional structure of the complex between human H-Ras bound to guanosine diphosphate and the guanosine triphosphatase (GTPase)-activating domain of the human GTPase-activating protein p120GAP (GAP-334) in the presence of aluminum fluoride was solved at a resolution of 2.5 angstroms. The structure shows the partly hydrophilic and partly hydrophobic nature of the communication between the two molecules, which explains the sensitivity of the interaction toward both salts and lipids. An arginine side chain (arginine-789) of GAP-334 is supplied into the active site of Ras to neutralize developing charges in the transition state. The switch II region of Ras is stabilized by GAP-334, thus allowing glutamine-61 of Ras, mutation of which activates the oncogenic potential, to participate in catalysis. The structural arrangement in the active site is consistent with a mostly associative mechanism of phosphoryl transfer and provides an explanation for the activation of Ras by glycine-12 and glutamine-61 mutations. Glycine-12 in the transition state mimic is within van der Waals distance of both arginine-789 of GAP-334 and glutamine-61 of Ras, and even its mutation to alanine would disturb the arrangements of residues in the transition state.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scheffzek, K -- Ahmadian, M R -- Kabsch, W -- Wiesmuller, L -- Lautwein, A -- Schmitz, F -- Wittinghofer, A -- New York, N.Y. -- Science. 1997 Jul 18;277(5324):333-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max-Planck-Institut fur molekulare Physiologie, Abteilung Strukturelle Biologie, Rheinlanddamm 201, 44139 Dortmund, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9219684" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Compounds/chemistry/metabolism ; Amino Acid Sequence ; Binding Sites ; Catalysis ; Cell Transformation, Neoplastic ; Crystallography, X-Ray ; Enzyme Activation ; Fluorides/chemistry/metabolism ; GTP Phosphohydrolases/chemistry/*metabolism ; GTP-Binding Proteins/chemistry/metabolism ; GTPase-Activating Proteins ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/metabolism ; Humans ; Models, Molecular ; Molecular Sequence Data ; Mutation ; *Protein Conformation ; Protein Structure, Secondary ; Proteins/*chemistry/*metabolism ; Signal Transduction ; ras GTPase-Activating Proteins ; ras Proteins/chemistry/genetics/*metabolism
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  • 22
    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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  • 23
    Publication Date: 1997-02-07
    Description: Many biological recognition interactions involve ligands and receptors that are tethered rather than rigidly bound on a cell surface. A surface forces apparatus was used to directly measure the force-distance interaction between a polymer-tethered ligand and its receptor. At separations near the fully extended tether length, the ligands rapidly lock onto their binding sites, pulling the ligand and receptor together. The measured interaction potential and its dynamics can be modeled with standard theories of polymer and colloidal interactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wong, J Y -- Kuhl, T L -- Israelachvili, J N -- Mullah, N -- Zalipsky, S -- GM 47334/GM/NIGMS NIH HHS/ -- GM17876/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Feb 7;275(5301):820-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA. jywong@engineering.ucsb.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9012346" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/chemistry/*metabolism ; Binding Sites ; Biotin/chemistry/*metabolism ; Chemistry, Physical ; Ligands ; Lipid Bilayers ; Mathematics ; Models, Chemical ; Molecular Conformation ; Physicochemical Phenomena ; Polyethylene Glycols/chemistry/*metabolism ; Streptavidin
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  • 24
    Publication Date: 1997-04-18
    Description: The three-dimensional structure of the enzyme 3-oxo-delta5-steroid isomerase (E.C. 5.3.3.1), a 28-kilodalton symmetrical dimer, was solved by multidimensional heteronuclear magnetic resonance spectroscopy. The two independently folded monomers pack together by means of extensive hydrophobic and electrostatic interactions. Each monomer comprises three alpha helices and a six-strand mixed beta-pleated sheet arranged to form a deep hydrophobic cavity. Catalytically important residues Tyr14 (general acid) and Asp38 (general base) are located near the bottom of the cavity and positioned as expected from mechanistic hypotheses. An unexpected acid group (Asp99) is also located in the active site adjacent to Tyr14, and kinetic and binding studies of the Asp99 to Ala mutant demonstrate that Asp99 contributes to catalysis by stabilizing the intermediate.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wu, Z R -- Ebrahimian, S -- Zawrotny, M E -- Thornburg, L D -- Perez-Alvarado, G C -- Brothers, P -- Pollack, R M -- Summers, M F -- GM38155/GM/NIGMS NIH HHS/ -- GM49082/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Apr 18;276(5311):415-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9103200" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Androstenedione/metabolism ; Binding Sites ; Dimerization ; Estradiol/metabolism ; Hydrogen Bonding ; Magnetic Resonance Spectroscopy ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; *Protein Conformation ; Protein Structure, Secondary ; Solutions ; Steroid Isomerases/*chemistry/genetics/metabolism
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  • 25
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-02-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Featherstone, C -- New York, N.Y. -- Science. 1997 Feb 21;275(5303):1066.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9054006" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallography, X-Ray ; Models, Molecular ; Phosphorylation ; *Protein Conformation ; Protein Structure, Secondary ; Protein-Tyrosine Kinases/chemistry ; Proto-Oncogene Proteins/chemistry ; Proto-Oncogene Proteins c-hck ; Proto-Oncogene Proteins pp60(c-src)/*chemistry/metabolism ; Tyrosine/chemistry/metabolism ; *src Homology Domains
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  • 26
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-02-07
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Service, R F -- New York, N.Y. -- Science. 1997 Feb 7;275(5301):756-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9036534" target="_blank"〉PubMed〈/a〉
    Keywords: Administration, Oral ; Amines/chemistry/metabolism/*therapeutic use ; Animals ; Antiviral Agents/chemistry/metabolism/*therapeutic use ; Binding Sites ; Clinical Trials as Topic ; Drug Design ; Drug Evaluation, Preclinical ; Humans ; Influenza, Human/*drug therapy ; Membrane Proteins/*genetics/physiology ; Molecular Structure ; Neuraminidase/*antagonists & inhibitors/chemistry/metabolism ; Orthomyxoviridae/*drug effects/enzymology ; Oseltamivir ; *Plant Proteins ; Protein Conformation
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  • 27
    Publication Date: 1997-01-24
    Description: A new paradigm for oxygen activation is required for enzymes such as methane monooxygenase (MMO), for which catalysis depends on a nonheme diiron center instead of the more familiar Fe-porphyrin cofactor. On the basis of precedents from synthetic diiron complexes, a high-valent Fe2(micro-O)2 diamond core has been proposed as the key oxidizing species for MMO and other nonheme diiron enzymes such as ribonucleotide reductase and fatty acid desaturase. The presence of a single short Fe-O bond (1.77 angstroms) per Fe atom and an Fe-Fe distance of 2.46 angstroms in MMO reaction intermediate Q, obtained from extended x-ray absorption fine structure and Mossbauer analysis, provides spectroscopic evidence that the diiron center in Q has an Fe2IVO2 diamond core.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shu, L -- Nesheim, J C -- Kauffmann, K -- Munck, E -- Lipscomb, J D -- Que, L Jr -- GM-08277/GM/NIGMS NIH HHS/ -- GM-22701/GM/NIGMS NIH HHS/ -- GM-40466/GM/NIGMS NIH HHS/ -- R01 GM040466/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1997 Jan 24;275(5299):515-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN 55455, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8999792" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Catalysis ; Crystallography, X-Ray ; Dimerization ; Gram-Negative Aerobic Bacteria/*enzymology ; Iron/*chemistry ; Molecular Structure ; Oxidation-Reduction ; Oxygen/*chemistry ; Oxygenases/*chemistry/metabolism ; Spectroscopy, Mossbauer ; Spectrum Analysis
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  • 28
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-07-04
    Description: Hepatocyte nuclear factors 1 and 4 (HNF-1 and HNF-4) are liver-enriched transcription factors that function in the regulation of several liver-specific genes. HNF-1 activates genes containing promoters with HNF-1 binding sites. However, this factor negatively regulates its own expression and that of other HNF-4-dependent genes that lack HNF-1 binding sites in their promoter region. This repression is exerted by a direct interaction of HNF-1 with AF2, the main activation domain of HNF-4. The dual functions of gene activation and repression suggest that HNF-1 is a global regulator of the transcriptional network involved in the maintenance of hepatocyte-specific phenotype.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ktistaki, E -- Talianidis, I -- New York, N.Y. -- Science. 1997 Jul 4;277(5322):109-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Post Office Box 1527, 711 10 Heraklion, Crete, Greece.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9204893" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; Binding Sites ; COS Cells ; *DNA-Binding Proteins ; *Gene Expression Regulation ; Hepatocyte Nuclear Factor 1 ; Hepatocyte Nuclear Factor 1-alpha ; Hepatocyte Nuclear Factor 1-beta ; Hepatocyte Nuclear Factor 4 ; Humans ; Liver/cytology/*metabolism ; Nuclear Proteins/genetics/metabolism ; Phosphoproteins/genetics/metabolism ; Promoter Regions, Genetic ; RNA, Messenger/genetics/metabolism ; Recombinant Fusion Proteins/metabolism ; Transcription Factors/*genetics/*metabolism ; Transcriptional Activation ; Tumor Cells, Cultured
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  • 29
    Publication Date: 1997-05-09
    Description: Timely deactivation of kinase cascades is crucial to the normal control of cell signaling and is partly accomplished by protein phosphatase 2A (PP2A). The catalytic (alpha) subunit of the serine-threonine kinase casein kinase 2 (CK2) bound to PP2A in vitro and in mitogen-starved cells; binding required the integrity of a sequence motif common to CK2alpha and SV40 small t antigen. Overexpression of CK2alpha resulted in deactivation of mitogen-activated protein kinase kinase (MEK) and suppression of cell growth. Moreover, CK2alpha inhibited the transforming activity of oncogenic Ras, but not that of constitutively activated MEK. Thus, CK2alpha may regulate the deactivation of the mitogen-activated protein kinase pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Heriche, J K -- Lebrin, F -- Rabilloud, T -- Leroy, D -- Chambaz, E M -- Goldberg, Y -- New York, N.Y. -- Science. 1997 May 9;276(5314):952-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Commissariat a l'Energie Atomique, Departement de Biologie Moleculaire et Structurale, Laboratoire de Biochimie des Regulations Cellulaires Endocrines, Unite 244, F-38054 Grenoble Cedex 9, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9139659" target="_blank"〉PubMed〈/a〉
    Keywords: 3T3 Cells ; Amino Acid Sequence ; Animals ; Antigens, Polyomavirus Transforming ; Binding Sites ; Casein Kinase II ; Cell Division ; Cell Transformation, Neoplastic ; MAP Kinase Kinase 1 ; Mice ; *Mitogen-Activated Protein Kinase Kinases ; Mutation ; Okadaic Acid/pharmacology ; Phosphoprotein Phosphatases/*metabolism ; Phosphorylation ; Platelet-Derived Growth Factor/pharmacology ; Protein Phosphatase 2 ; Protein-Serine-Threonine Kinases/*metabolism/pharmacology ; Protein-Tyrosine Kinases/metabolism/pharmacology ; Recombinant Fusion Proteins/metabolism ; Transfection ; ras Proteins/pharmacology
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  • 30
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-04-04
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jayaram, M -- New York, N.Y. -- Science. 1997 Apr 4;276(5309):49-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, University of Texas at Austin, Austin, TX 78712, USA. jayaram@almach.cc.utexas.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9122709" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriophage lambda/*enzymology ; Binding Sites ; Crystallography, X-Ray ; DNA/*metabolism ; DNA Nucleotidyltransferases/chemistry/metabolism ; DNA, Circular/metabolism ; Integrases/*chemistry/metabolism ; Models, Molecular ; *Protein Conformation ; Recombinases ; *Recombination, Genetic ; Tyrosine/metabolism ; Virus Integration
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  • 31
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-06-13
    Description: Intron excision is an essential step in eukaryotic gene expression, but the molecular mechanisms by which the spliceosome accurately identifies splice sites in nuclear precursors to messenger RNAs (pre-mRNAs) are not well understood. A bimolecular assay for the second step of splicing has now revealed that exon ligation by the human spliceosome does not require covalent attachment of a 3' splice site to the branch site. Furthermore, accurate definition of the 3' splice site in this system is independent of either a covalently attached polypyrimidine tract or specific 3' exon sequences. Rather, in this system 3' splice site selection apparently occurs with a 5' --〉 3' directionality.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anderson, K -- Moore, M J -- GM53007/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jun 13;276(5319):1712-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉W. M. Keck Institute for Cellular Visualization, Department of Biochemistry, Brandeis University, Waltham, MA 02254, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9180084" target="_blank"〉PubMed〈/a〉
    Keywords: Adenoviridae/genetics ; Base Sequence ; Binding Sites ; *Exons ; Humans ; Introns ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA Precursors/genetics/*metabolism ; *RNA Splicing ; Spliceosomes/*metabolism
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  • 32
    Publication Date: 1997-12-31
    Description: Methyl-coenzyme M reductase (MCR), the enzyme responsible for the microbial formation of methane, is a 300-kilodalton protein organized as a hexamer in an alpha2beta2gamma2 arrangement. The crystal structure of the enzyme from Methanobacterium thermoautotrophicum, determined at 1.45 angstrom resolution for the inactive enzyme state MCRox1-silent, reveals that two molecules of the nickel porphinoid coenzyme F430 are embedded between the subunits alpha, alpha', beta, and gamma and alpha', alpha, beta', and gamma', forming two identical active sites. Each site is accessible for the substrate methyl-coenzyme M through a narrow channel locked after binding of the second substrate coenzyme B. Together with a second structurally characterized enzyme state (MCRsilent) containing the heterodisulfide of coenzymes M and B, a reaction mechanism is proposed that uses a radical intermediate and a nickel organic compound.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ermler, U -- Grabarse, W -- Shima, S -- Goubeaud, M -- Thauer, R K -- New York, N.Y. -- Science. 1997 Nov 21;278(5342):1457-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max-Planck-Institut fur Biophysik, Heinrich-Hoffmann-Strabetae 7, 60528 Frankfurt, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9367957" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Catalysis ; Coenzymes/chemistry/metabolism ; Crystallography, X-Ray ; Disulfides/chemistry/metabolism ; Hydrogen/metabolism ; Hydrogen Bonding ; Ligands ; Mesna/analogs & derivatives/chemistry/metabolism ; Metalloporphyrins/chemistry/metabolism ; Methane/*metabolism ; Methanobacterium/*enzymology ; Models, Molecular ; Nickel/chemistry/metabolism ; Oxidation-Reduction ; Oxidoreductases/*chemistry/*metabolism ; Phosphothreonine/analogs & derivatives/chemistry/metabolism ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary
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  • 33
    Publication Date: 1997-04-11
    Description: The proline-rich COOH-terminal region of dynamin binds various Src homology 3 (SH3) domain-containing proteins, but the physiological role of these interactions is unknown. In living nerve terminals, the function of the interaction with SH3 domains was examined. Amphiphysin contains an SH3 domain and is a major dynamin binding partner at the synapse. Microinjection of amphiphysin's SH3 domain or of a dynamin peptide containing the SH3 binding site inhibited synaptic vesicle endocytosis at the stage of invaginated clathrin-coated pits, which resulted in an activity-dependent distortion of the synaptic architecture and a depression of transmitter release. These findings demonstrate that SH3-mediated interactions are required for dynamin function and support an essential role of clathrin-mediated endocytosis in synaptic vesicle recycling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shupliakov, O -- Low, P -- Grabs, D -- Gad, H -- Chen, H -- David, C -- Takei, K -- De Camilli, P -- Brodin, L -- CA46128/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1997 Apr 11;276(5310):259-63.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9092476" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Cell Membrane/ultrastructure ; Coated Pits, Cell-Membrane/ultrastructure ; Dynamins ; *Endocytosis ; GTP Phosphohydrolases/*metabolism ; Humans ; Lampreys ; Microscopy, Electron ; Molecular Sequence Data ; Nerve Tissue Proteins/chemistry/*metabolism ; Proline/chemistry ; Recombinant Fusion Proteins/metabolism ; Synapses/metabolism/ultrastructure ; Synaptic Transmission ; Synaptic Vesicles/*metabolism/ultrastructure ; *src Homology Domains
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  • 34
    Publication Date: 1997-11-05
    Description: The carboxyl-terminal domain, residues 146 to 231, of the human immunodeficiency virus-1 (HIV-1) capsid protein [CA(146-231)] is required for capsid dimerization and viral assembly. This domain contains a stretch of 20 residues, called the major homology region (MHR), which is conserved across retroviruses and is essential for viral assembly, maturation, and infectivity. The crystal structures of CA(146-231) and CA(151-231) reveal that the globular domain is composed of four helices and an extended amino-terminal strand. CA(146-231) dimerizes through parallel packing of helix 2 across a dyad. The MHR is distinct from the dimer interface and instead forms an intricate hydrogen-bonding network that interconnects strand 1 and helices 1 and 2. Alignment of the CA(146-231) dimer with the crystal structure of the capsid amino-terminal domain provides a model for the intact protein and extends models for assembly of the central conical core of HIV-1.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gamble, T R -- Yoo, S -- Vajdos, F F -- von Schwedler, U K -- Worthylake, D K -- Wang, H -- McCutcheon, J P -- Sundquist, W I -- Hill, C P -- R01 AI40333/AI/NIAID NIH HHS/ -- R01 AI43036/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1997 Oct 31;278(5339):849-53.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Utah, Salt Lake City, UT 84132, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9346481" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Capsid/*chemistry/genetics ; Cell Line ; Cloning, Molecular ; Cloning, Organism ; Crystallography, X-Ray ; Dimerization ; HIV-1/*chemistry/genetics/physiology ; Humans ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Peptidylprolyl Isomerase/chemistry ; *Protein Conformation ; Virus Replication
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  • 35
    Publication Date: 1997-09-05
    Description: The 4,639,221-base pair sequence of Escherichia coli K-12 is presented. Of 4288 protein-coding genes annotated, 38 percent have no attributed function. Comparison with five other sequenced microbes reveals ubiquitous as well as narrowly distributed gene families; many families of similar genes within E. coli are also evident. The largest family of paralogous proteins contains 80 ABC transporters. The genome as a whole is strikingly organized with respect to the local direction of replication; guanines, oligonucleotides possibly related to replication and recombination, and most genes are so oriented. The genome also contains insertion sequence (IS) elements, phage remnants, and many other patches of unusual composition indicating genome plasticity through horizontal transfer.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blattner, F R -- Plunkett, G 3rd -- Bloch, C A -- Perna, N T -- Burland, V -- Riley, M -- Collado-Vides, J -- Glasner, J D -- Rode, C K -- Mayhew, G F -- Gregor, J -- Davis, N W -- Kirkpatrick, H A -- Goeden, M A -- Rose, D J -- Mau, B -- Shao, Y -- P01 HG01428/HG/NHGRI NIH HHS/ -- S10 RR10379/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 5;277(5331):1453-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Genetics, University of Wisconsin-Madison, 445 Henry Mall, Madison, WI 53706, USA. ecoli@genetics.wisc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9278503" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/chemistry/genetics/metabolism ; Bacteriophage lambda/genetics ; Base Composition ; Binding Sites ; Chromosome Mapping ; DNA Replication ; DNA Transposable Elements ; DNA, Bacterial/genetics ; Escherichia coli/*genetics ; Genes, Bacterial ; *Genome, Bacterial ; Molecular Sequence Data ; Mutation ; Operon ; RNA, Bacterial/genetics ; RNA, Transfer/genetics ; Recombination, Genetic ; Regulatory Sequences, Nucleic Acid ; Repetitive Sequences, Nucleic Acid ; *Sequence Analysis, DNA ; Sequence Homology, Amino Acid
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  • 36
    Publication Date: 1997-03-07
    Description: The blue-light photoreceptor photoactive yellow protein (PYP) undergoes a self-contained light cycle. The atomic structure of the bleached signaling intermediate in the light cycle of PYP was determined by millisecond time-resolved, multiwavelength Laue crystallography and simultaneous optical spectroscopy. Light-induced trans-to-cis isomerization of the 4-hydroxycinnamyl chromophore and coupled protein rearrangements produce a new set of active-site hydrogen bonds. An arginine gateway opens, allowing solvent exposure and protonation of the chromophore's phenolic oxygen. Resulting changes in shape, hydrogen bonding, and electrostatic potential at the protein surface form a likely basis for signal transduction. The structural results suggest a general framework for the interpretation of protein photocycles.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Genick, U K -- Borgstahl, G E -- Ng, K -- Ren, Z -- Pradervand, C -- Burke, P M -- Srajer, V -- Teng, T Y -- Schildkamp, W -- McRee, D E -- Moffat, K -- Getzoff, E D -- GM36452/GM/NIGMS NIH HHS/ -- GM37684/GM/NIGMS NIH HHS/ -- RR07707/RR/NCRR NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1997 Mar 7;275(5305):1471-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, 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/9045611" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*chemistry/physiology ; Binding Sites ; Chromatiaceae ; Crystallography, X-Ray ; Electrochemistry ; Hydrogen Bonding ; Isomerism ; Light ; Models, Molecular ; *Photoreceptors, Microbial ; *Protein Conformation ; Signal Transduction ; Spectrum Analysis
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  • 37
    Publication Date: 1997-02-28
    Description: Formate dehydrogenase H from Escherichia coli contains selenocysteine (SeCys), molybdenum, two molybdopterin guanine dinucleotide (MGD) cofactors, and an Fe4S4 cluster at the active site and catalyzes the two-electron oxidation of formate to carbon dioxide. The crystal structures of the oxidized [Mo(VI), Fe4S4(ox)] form of formate dehydrogenase H (with and without bound inhibitor) and the reduced [Mo(IV), Fe4S4(red)] form have been determined, revealing a four-domain alphabeta structure with the molybdenum directly coordinated to selenium and both MGD cofactors. These structures suggest a reaction mechanism that directly involves SeCys140 and His141 in proton abstraction and the molybdenum, molybdopterin, Lys44, and the Fe4S4 cluster in electron transfer.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Boyington, J C -- Gladyshev, V N -- Khangulov, S V -- Stadtman, T C -- Sun, P D -- New York, N.Y. -- Science. 1997 Feb 28;275(5304):1305-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Structure, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Rockville, MD 20852, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9036855" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Carbon Dioxide/metabolism ; Catalysis ; Crystallography, X-Ray ; Electron Transport ; Escherichia coli/enzymology ; Ferrous Compounds/*chemistry ; Formate Dehydrogenases/*chemistry/metabolism ; Formates/*metabolism ; Guanine Nucleotides/chemistry/metabolism ; Hydrogen Bonding ; Hydrogenase/*chemistry/metabolism ; Ligands ; Models, Molecular ; Molecular Sequence Data ; Molybdenum/chemistry/metabolism ; Multienzyme Complexes/*chemistry/metabolism ; Nitrites/chemistry ; Oxidation-Reduction ; *Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protons ; Pterins/chemistry/metabolism ; Selenocysteine/chemistry/metabolism
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  • 38
    Publication Date: 1997-04-18
    Description: The crystal structure of the arabinose-binding and dimerization domain of the Escherchia coli gene regulatory protein AraC was determined in the presence and absence of L-arabinose. The 1.5 angstrom structure of the arabinose-bound molecule shows that the protein adopts an unusual fold, binding sugar within a beta barrel and completely burying the arabinose with the amino-terminal arm of the protein. Dimer contacts in the presence of arabinose are mediated by an antiparallel coiled-coil. In the 2.8 angstrom structure of the uncomplexed protein, the amino-terminal arm is disordered, uncovering the sugar-binding pocket and allowing it to serve as an oligomerization interface. The ligand-gated oligomerization as seen in AraC provides the basis of a plausible mechanism for modulating the protein's DNA-looping properties.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Soisson, S M -- MacDougall-Shackleton, B -- Schleif, R -- Wolberger, C -- GM18277/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Apr 18;276(5311):421-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biophysics and Biophysical Chemistry, 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/9103202" target="_blank"〉PubMed〈/a〉
    Keywords: AraC Transcription Factor ; Arabinose/metabolism ; *Bacterial Proteins ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; DNA/*metabolism ; Dimerization ; Hydrogen Bonding ; Ligands ; Models, Molecular ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Repressor Proteins/*chemistry/metabolism ; *Transcription Factors
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  • 39
    Publication Date: 1997-05-02
    Description: To study nucleosome mobility and positioning, the R3 lac repressor was used with an adenosine triphosphate (ATP)-dependent chromatin assembly system to establish the positioning of five nucleosomes, with one nucleosome located between two R3 lac operators. When R3 protein was dissociated from DNA with isopropyl beta-D-thiogalactopyranoside, the R3-induced nucleosome positions remained unchanged for at least 60 minutes in the absence of ATP but rearranged within 15 minutes in the presence of ATP. These results suggest that nucleosomes are dynamic and mobile rather than static and that a DNA binding factor is continuously required for the maintenance of nucleosome positioning.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pazin, M J -- Bhargava, P -- Geiduschek, E P -- Kadonaga, J T -- New York, N.Y. -- Science. 1997 May 2;276(5313):809-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9115208" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Apyrase/metabolism ; Binding Sites ; Chromatin/*metabolism ; DNA/*metabolism ; DNA-Binding Proteins/*metabolism ; Isopropyl Thiogalactoside/pharmacology ; Nucleosomes/*physiology ; Operator Regions, Genetic ; Repressor Proteins/*metabolism
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  • 40
    Publication Date: 1997-04-04
    Description: Lambda integrase is archetypic of site-specific recombinases that catalyze intermolecular DNA rearrangements without energetic input. DNA cleavage, strand exchange, and religation steps are linked by a covalent phosphotyrosine intermediate in which Tyr342 is attached to the 3'-phosphate of the DNA cut site. The 1.9 angstrom crystal structure of the integrase catalytic domain reveals a protein fold that is conserved in organisms ranging from archaebacteria to yeast and that suggests a model for interaction with target DNA. The attacking Tyr342 nucleophile is located on a flexible loop about 20 angstroms from a basic groove that contains all the other catalytically essential residues. This bipartite active site can account for several apparently paradoxical features of integrase family recombinases, including the capacity for both cis and trans cleavage of DNA.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1839824/" 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/PMC1839824/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kwon, H J -- Tirumalai, R -- Landy, A -- Ellenberger, T -- AI13544/AI/NIAID NIH HHS/ -- GM33928/GM/NIGMS NIH HHS/ -- R01 GM033928/GM/NIGMS NIH HHS/ -- R01 GM062723/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Apr 4;276(5309):126-31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9082984" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Attachment Sites, Microbiological ; Bacteriophage lambda/*enzymology ; Binding Sites ; Cloning, Molecular ; Conserved Sequence ; Crystallography, X-Ray ; DNA/*metabolism ; DNA Nucleotidyltransferases/chemistry/metabolism ; Hydrogen Bonding ; Integrases/*chemistry/metabolism ; Models, Molecular ; Molecular Sequence Data ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Recombinases ; *Recombination, Genetic ; Tyrosine/chemistry/metabolism ; Virus Integration
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  • 41
    Publication Date: 1997-01-03
    Description: The oriented peptide library technique was used to investigate the peptide-binding specificities of nine PDZ domains. Each PDZ domain selected peptides with hydrophobic residues at the carboxyl terminus. Individual PDZ domains selected unique optimal motifs defined primarily by the carboxyl terminal three to seven residues of the peptides. One family of PDZ domains, including those of the Discs Large protein, selected peptides with the consensus motif Glu-(Ser/Thr)-Xxx-(Val/Ile) (where Xxx represents any amino acid) at the carboxyl terminus. In contrast, another family of PDZ domains, including those of LIN-2, p55, and Tiam-1, selected peptides with hydrophobic or aromatic side chains at the carboxyl terminal three residues. On the basis of crystal structures of the PSD-95-3 PDZ domain, the specificities observed with the peptide library can be rationalized.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Songyang, Z -- Fanning, A S -- Fu, C -- Xu, J -- Marfatia, S M -- Chishti, A H -- Crompton, A -- Chan, A C -- Anderson, J M -- Cantley, L C -- CA66263/CA/NCI NIH HHS/ -- DK34989/DK/NIDDK NIH HHS/ -- R01 GM056203/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Jan 3;275(5296):73-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Signal Transduction, Beth Israel Hospital, and Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8974395" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Crystallography, X-Ray ; Guanine Nucleotide Exchange Factors ; Guanylate Kinase ; Helminth Proteins/chemistry/metabolism ; Humans ; Kinesin/chemistry/metabolism ; Membrane Proteins/chemistry/metabolism ; Models, Molecular ; Myosins/chemistry/metabolism ; Nerve Tissue Proteins/chemistry/metabolism ; Nucleoside-Phosphate Kinase/chemistry/metabolism ; Peptide Library ; Peptides/chemistry/*metabolism ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protein Tyrosine Phosphatases/chemistry/metabolism ; Proteins/chemistry/*metabolism ; Sequence Homology, Amino Acid
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  • 42
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-07-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sprang, S R -- New York, N.Y. -- Science. 1997 Jul 18;277(5324):329-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Texas Southwestern Medical School, Dallas, TX 75235, USA. sprang@howie.swmed.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9518363" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Compounds/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Fluorides/metabolism ; GTP Phosphohydrolases/*metabolism ; GTP-Binding Proteins/chemistry/*metabolism ; GTPase-Activating Proteins ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/*metabolism ; Hydrolysis ; Models, Molecular ; Protein Conformation ; Protein Structure, Secondary ; Proteins/*chemistry/metabolism ; *RGS Proteins ; ras GTPase-Activating Proteins ; ras Proteins/chemistry/*metabolism
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  • 43
    Publication Date: 1997-09-20
    Description: Terpene cyclases catalyze the synthesis of cyclic terpenes with 10-, 15-, and 20-carbon acyclic isoprenoid diphosphates as substrates. Plants have been a source of these natural products by providing a homologous set of terpene synthases. The crystal structures of 5-epi-aristolochene synthase, a sesquiterpene cyclase from tobacco, alone and complexed separately with two farnesyl diphosphate analogs were analyzed. These structures reveal an unexpected enzymatic mechanism for the synthesis of the bicyclic product, 5-epi-aristolochene, and provide a basis for understanding the stereochemical selectivity displayed by other cyclases in the biosynthesis of pharmacologically important cyclic terpenes. As such, these structures provide templates for the engineering of novel terpene cyclases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Starks, C M -- Back, K -- Chappell, J -- Noel, J P -- GM07240/GM/NIGMS NIH HHS/ -- GM54029/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 19;277(5333):1815-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Structural Biology Laboratory, The Salk Institute for Biological Studies, 10010 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/9295271" target="_blank"〉PubMed〈/a〉
    Keywords: *Alkyl and Aryl Transferases ; Binding Sites ; Chemistry, Physical ; Crystallization ; Crystallography, X-Ray ; Cyclization ; Magnesium/metabolism ; Models, Molecular ; Physicochemical Phenomena ; *Plants, Toxic ; Polyisoprenyl Phosphates/metabolism ; *Protein Conformation ; Protein Structure, Secondary ; Protons ; Sesquiterpenes/*chemical synthesis ; Tobacco/*enzymology ; Transferases/*chemistry/metabolism
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  • 44
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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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  • 45
    Publication Date: 1997-09-20
    Description: The crystal structure of pentalenene synthase at 2.6 angstrom resolution reveals critical active site features responsible for the cyclization of farnesyl diphosphate into the tricyclic hydrocarbon pentalenene. Metal-triggered substrate ionization initiates catalysis, and the alpha-barrel active site serves as a template to channel and stabilize the conformations of reactive carbocation intermediates through a complex cyclization cascade. The core active site structure of the enzyme may be preserved among the greater family of terpenoid synthases, possibly implying divergence from a common ancestral synthase to satisfy biological requirements for increasingly diverse natural products.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lesburg, C A -- Zhai, G -- Cane, D E -- Christianson, D W -- New York, N.Y. -- Science. 1997 Sep 19;277(5333):1820-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9295272" target="_blank"〉PubMed〈/a〉
    Keywords: *Alkyl and Aryl Transferases ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; Cyclization ; Cyclopentanes/chemical synthesis/chemistry ; Geranyltranstransferase ; *Intramolecular Lyases ; Isomerases/*chemistry/metabolism ; Models, Molecular ; Polyisoprenyl Phosphates/chemistry/metabolism ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Recombinant Proteins/chemistry/metabolism ; Sesquiterpenes ; Streptomyces/*enzymology ; Transferases/chemistry/metabolism
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  • 46
    Publication Date: 1997-01-31
    Description: A method is described for selecting DNA-binding proteins that recognize desired sequences. The protocol involves gradually extending a new zinc finger protein across the desired 9- or 10-base pair target site, adding and optimizing one finger at a time. This procedure was tested with a TATA box, a p53 binding site, and a nuclear receptor element, and proteins were obtained that bind with nanomolar dissociation constants and discriminate effectively (greater than 20,000-fold) against nonspecific DNA. This strategy may provide important information about protein-DNA recognition as well as powerful tools for biomedical research.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Greisman, H A -- Pabo, C O -- New York, N.Y. -- Science. 1997 Jan 31;275(5300):657-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9005850" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Composition ; Base Sequence ; Binding Sites ; DNA/*metabolism ; DNA-Binding Proteins/chemistry/*metabolism ; Genes, p53 ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; Peptide Library ; Protein Conformation ; *Protein Engineering ; Protein Structure, Secondary ; Receptors, Cytoplasmic and Nuclear/genetics ; TATA Box ; Transcription Factors/chemistry/metabolism ; *Zinc Fingers
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  • 47
    Publication Date: 1997-05-02
    Description: High resolution x-ray diffraction data from crystals of the Rhodobacter sphaeroides photosynthetic reaction center (RC) have been collected at cryogenic temperature in the dark and under illumination, and the structures were refined at 2.2 and 2.6 angstrom resolution, respectively. In the charge-separated D+QAQB- state (where D is the primary electron donor (a bacteriochlorophyll dimer), and QA and QB are the primary and secondary quinone acceptors, respectively), QB- is located approximately 5 angstroms from the QB position in the charge-neutral (DQAQB) state, and has undergone a 180 degrees propeller twist around the isoprene chain. A model based on the difference between the two structures is proposed to explain the observed kinetics of electron transfer from QA-QB to QAQB- and the relative binding affinities of the different ubiquinone species in the QB pocket. In addition, several water channels (putative proton pathways) leading from the QB pocket to the surface of the RC were delineated, one of which leads directly to the membrane surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stowell, M H -- McPhillips, T M -- Rees, D C -- Soltis, S M -- Abresch, E -- Feher, G -- GM13191/GM/NIGMS NIH HHS/ -- GM45162/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 May 2;276(5313):812-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Chemistry and Chemical Engineering, 147-75CH, 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/9115209" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Cell Membrane/chemistry ; Crystallization ; Crystallography, X-Ray ; Darkness ; Electron Transport ; Freezing ; Hydrogen Bonding ; *Light ; Light-Harvesting Protein Complexes ; Models, Molecular ; Photosynthetic Reaction Center Complex Proteins/*chemistry/metabolism ; *Protein Conformation ; *Protons ; Rhodobacter sphaeroides/*chemistry ; Temperature ; Ubiquinone/chemistry/metabolism
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  • 48
    Publication Date: 1997-10-10
    Description: The histidine triad (HIT) protein family is among the most ubiquitous and highly conserved in nature, but a biological activity has not yet been identified for any member of the HIT family. Fragile histidine triad protein (FHIT) and protein kinase C interacting protein (PKCI) were used in a structure-based approach to elucidate characteristics of in vivo ligands and reactions. Crystallographic structures of apo, substrate analog, pentacovalent transition-state analog, and product states of both enzymes reveal a catalytic mechanism and define substrate characteristics required for catalysis, thus unifying the HIT family as nucleotidyl hydrolases, transferases, or both. The approach described here may be useful in identifying structure-function relations between protein families identified through genomics.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lima, C D -- Klein, M G -- Hendrickson, W A -- T32CA09503/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1997 Oct 10;278(5336):286-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9323207" target="_blank"〉PubMed〈/a〉
    Keywords: *Acid Anhydride Hydrolases ; Adenosine/metabolism ; Adenosine Diphosphate/analogs & derivatives/metabolism ; Adenosine Monophosphate/metabolism ; Adenosine Triphosphate/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Dimerization ; Dinucleoside Phosphates/metabolism ; Hydrogen Bonding ; *Neoplasm Proteins ; Nerve Tissue Proteins/chemistry/*metabolism ; Protein Structure, Secondary ; Proteins/chemistry/*metabolism ; Structure-Activity Relationship ; Substrate Specificity ; Tungsten Compounds/metabolism
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  • 49
    Publication Date: 1997-02-21
    Description: The x-ray structures of three esterase-like catalytic antibodies identified by screening for catalytic activity the entire hybridoma repertoire, elicited in response to a phosphonate transition state analog (TSA) hapten, were analyzed. The high resolution structures account for catalysis by transition state stabilization, and in all three antibodies a tyrosine residue participates in the oxyanion hole. Despite significant conformational differences in their combining sites, the three antibodies, which are the most efficient among those elicited, achieve catalysis in essentially the same mode, suggesting that evolution for binding to a single TSA followed by screening for catalysis lead to antibodies with structural convergence.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Charbonnier, J B -- Golinelli-Pimpaneau, B -- Gigant, B -- Tawfik, D S -- Chap, R -- Schindler, D G -- Kim, S H -- Green, B S -- Eshhar, Z -- Knossow, M -- New York, N.Y. -- Science. 1997 Feb 21;275(5303):1140-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire d'Enzymologie et de Biochimie Structurales, CNRS, 91198 Gif sur Yvette Cedex, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9027317" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Catalytic/*chemistry/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Enzyme-Linked Immunosorbent Assay ; *Evolution, Molecular ; Haptens/chemistry/metabolism ; Hydrogen Bonding ; Immunoglobulin Fab Fragments/chemistry/metabolism ; Mice ; Mice, Inbred BALB C ; Models, Molecular ; Organophosphonates/chemistry/metabolism ; *Protein Conformation ; Tyrosine/chemistry
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  • 50
    Publication Date: 1997-02-14
    Description: A cytochrome c oxidase model that consists of a cobalt(II) porphyrin with a copper(I) triazacyclononane macrocycle fastened on the distal face and an imidazole covalently attached to the proximal face has been synthesized and characterized. Redox titrations with molecular oxygen (O2) and cobaltocene were carried out, and O2 was found to bind irreversibly in a 1:1 ratio to the model compound. This O2 adduct (a bridged peroxide) can be fully reduced to the deoxygenated form with four equivalents of cobaltocene. The model compound was adsorbed on an edge-plane graphite electrode, and rotating ring-disk voltammetry was used to monitor the electrocatalytic reduction of O2. Four-electron reduction of O2 was observed at physiological pH.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Collman, J P -- Fu, L -- Herrmann, P C -- Zhang, X -- 5R37 GM-17880-26/GM/NIGMS NIH HHS/ -- CHE9123187-A2/PHS HHS/ -- RR 04122/RR/NCRR NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1997 Feb 14;275(5302):949-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Stanford University, Stanford, CA 94305, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9020071" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Bridged Compounds/chemical synthesis/*chemistry ; Catalysis ; Cobalt/chemistry ; Copper/chemistry ; Electron Transport Complex IV/chemistry/*metabolism ; Electrons ; Hydrogen-Ion Concentration ; Oxidation-Reduction ; Oxygen/chemistry/*metabolism ; Porphyrins/chemical synthesis/*chemistry
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  • 51
    Publication Date: 1997-10-23
    Description: The nitric oxide synthase oxygenase domain (NOSox) oxidizes arginine to synthesize the cellular signal and defensive cytotoxin nitric oxide (NO). Crystal structures determined for cytokine-inducible NOSox reveal an unusual fold and heme environment for stabilization of activated oxygen intermediates key for catalysis. A winged beta sheet engenders a curved alpha-beta domain resembling a baseball catcher's mitt with heme clasped in the palm. The location of exposed hydrophobic residues and the results of mutational analysis place the dimer interface adjacent to the heme-binding pocket. Juxtaposed hydrophobic O2- and polar L-arginine-binding sites occupied by imidazole and aminoguanidine, respectively, provide a template for designing dual-function inhibitors and imply substrate-assisted catalysis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Crane, B R -- Arvai, A S -- Gachhui, R -- Wu, C -- Ghosh, D K -- Getzoff, E D -- Stuehr, D J -- Tainer, J A -- CA53914/CA/NCI NIH HHS/ -- HL58883/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1997 Oct 17;278(5337):425-31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9334294" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Arginine/chemistry/metabolism ; Binding Sites ; Biopterin/analogs & derivatives/metabolism ; *Caenorhabditis elegans Proteins ; Catalysis ; Crystallography, X-Ray ; Dimerization ; Enzyme Induction ; Enzyme Inhibitors/metabolism ; Guanidines/metabolism ; Heme/chemistry ; Homeodomain Proteins/chemistry/*genetics/physiology ; Hydrogen Bonding ; Imidazoles/metabolism ; Isoenzymes/antagonists & inhibitors/*chemistry/metabolism ; Models, Molecular ; Molecular Sequence Data ; Nitric Oxide Synthase/antagonists & inhibitors/*chemistry/metabolism ; Oxidation-Reduction ; Oxygen/metabolism ; Oxygenases/chemistry/metabolism ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary
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  • 52
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-10-06
    Description: Ste5 is a scaffold for the mitogen-activated protein kinase (MAPK) cascade components in a yeast pheromone response pathway. Ste5 also associates with Ste4, the beta subunit of a heterotrimeric guanine nucleotide-binding protein, potentially linking receptor activation to stimulation of the MAPK cascade. A RING-H2 motif at the Ste5 amino terminus is apparently essential for function because Ste5(C177S) and Ste5(C177A C180A) mutants did not rescue the mating defect of a ste5Delta cell. In vitro Ste5(C177A C180A) bound each component of the MAPK cascade, but not Ste4. Unlike wild-type Ste5, the mutant did not appear to oligomerize; however, when fused to a heterologous dimerization domain (glutathione S-transferase), the chimeric protein restored mating in an ste5Delta cell and an ste4Delta ste5Delta double mutant. Thus, the RING-H2 domain mediates Ste4-Ste5 interaction, which is a prerequisite for Ste5-Ste5 self-association and signaling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Inouye, C -- Dhillon, N -- Thorner, J -- CA09041/CA/NCI NIH HHS/ -- GM21841/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Oct 3;278(5335):103-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720-3202, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9311911" target="_blank"〉PubMed〈/a〉
    Keywords: *Adaptor Proteins, Signal Transducing ; Amino Acid Sequence ; Binding Sites ; Calcium-Calmodulin-Dependent Protein Kinases/metabolism ; *Carrier Proteins ; Dimerization ; Fungal Proteins/*chemistry/genetics/*metabolism ; *GTP-Binding Protein beta Subunits ; GTP-Binding Proteins/*metabolism ; Genetic Complementation Test ; Glutathione Transferase/chemistry ; *Heterotrimeric GTP-Binding Proteins ; Molecular Sequence Data ; Peptides/*physiology ; Pheromones/physiology ; Point Mutation ; Polymers ; Recombinant Fusion Proteins/metabolism ; Saccharomyces cerevisiae/chemistry/genetics/*metabolism ; *Saccharomyces cerevisiae Proteins ; *Signal Transduction ; Transformation, Genetic
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  • 53
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-06-20
    Description: The plant hormone auxin regulates plant physiology by modulating the interaction of transcription factors with auxin response elements (AuxREs) of the affected genes. A transcription factor, Auxin Response Factor 1 (ARF1), that binds to the sequence TGTCTC in AuxREs was cloned from Arabidopsis by using a yeast one-hybrid system. ARF1 has an amino-terminal DNA-binding domain related to the carboxyl terminus of the maize transactivator Viviparous-1. Sequence requirements for ARF1 binding in vitro are identical to those that confer auxin responsiveness in vivo. The carboxyl terminus of ARF1 contains two motifs found in the Aux/IAA class of proteins and appears to mediate protein-protein interactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ulmasov, T -- Hagen, G -- Guilfoyle, T J -- New York, N.Y. -- Science. 1997 Jun 20;276(5320):1865-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Missouri, 117 Schweitzer Hall, Columbia, MO 65211, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9188533" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Arabidopsis/genetics ; Arabidopsis Proteins ; Base Sequence ; Binding Sites ; Cloning, Molecular ; DNA, Plant/genetics/*metabolism ; DNA-Binding Proteins/chemistry/genetics/*metabolism ; Genes, Plant ; Indoleacetic Acids/*pharmacology ; Molecular Sequence Data ; Mutation ; Plant Proteins ; *Promoter Regions, Genetic ; *Repetitive Sequences, Nucleic Acid ; Transcription Factors/chemistry/genetics/*metabolism
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  • 54
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-02-14
    Description: In the yeast Saccharomyces cerevisiae, telomere elongation is negatively regulated by the telomere repeat-binding protein Rap1p, such that a narrow length distribution of telomere repeat tracts is observed. This length regulation was shown to function independently of the orientation of the telomere repeats. The number of repeats at an individual telomere was reduced when hybrid proteins containing the Rap1p carboxyl terminus were targeted there by a heterologous DNA-binding domain. The extent of this telomere tract shortening was proportional to the number of targeted molecules, consistent with a feedback mechanism of telomere length regulation that can discriminate the precise number of Rap1p molecules bound to the chromosome end.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marcand, S -- Gilson, E -- Shore, D -- GM40094/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Feb 14;275(5302):986-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9020083" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Chromosomes, Fungal/metabolism ; Fungal Proteins/*metabolism ; GTP-Binding Proteins/*metabolism ; Gene Expression Regulation, Fungal ; Genetic Markers ; Mutation ; Saccharomyces cerevisiae/genetics/*metabolism ; Telomerase/metabolism ; Telomere/*metabolism ; Transformation, Genetic ; rap GTP-Binding Proteins
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  • 55
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-09-20
    Description: The crystal structure of squalene-hopene cyclase from Alicyclobacillus acidocaldarius was determined at 2.9 angstrom resolution. The mechanism and sequence of this cyclase are closely related to those of 2,3-oxidosqualene cyclases that catalyze the cyclization step in cholesterol biosynthesis. The structure reveals a membrane protein with membrane-binding characteristics similar to those of prostaglandin-H2 synthase, the only other reported protein of this type. The active site of the enzyme is located in a large central cavity that is of suitable size to bind squalene in its required conformation and that is lined by aromatic residues. The structure supports a mechanism in which the acid starting the reaction by protonating a carbon-carbon double bond is an aspartate that is coupled to a histidine. Numerous surface alpha helices are connected by characteristic QW-motifs (Q is glutamine and W is tryptophan) that tighten the protein structure, possibly for absorbing the reaction energy without structural damage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wendt, K U -- Poralla, K -- Schulz, G E -- New York, N.Y. -- Science. 1997 Sep 19;277(5333):1811-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Organische Chemie und Biochemie, Albertstrasse 21, D-79104 Freiburg im Breisgau, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9295270" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacillaceae/*enzymology ; Binding Sites ; Cell Membrane/enzymology ; Crystallization ; Crystallography, X-Ray ; Cyclization ; Dimerization ; Humans ; Hydrogen Bonding ; *Intramolecular Transferases ; Isomerases/*chemistry/metabolism ; Models, Molecular ; Molecular Sequence Data ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Recombinant Proteins/chemistry/metabolism ; Sequence Alignment ; Squalene/metabolism ; Thermodynamics
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  • 56
    Publication Date: 1997-11-14
    Description: Cleland and Kreevoy recently advanced the idea that a special type of hydrogen bond (H-bond), termed a low-barrier hydrogen bond (LBHB), may account for the "missing" transition state stabilization underlying the catalytic power of many enzymes, and Frey et al. have proposed that the H-bond between aspartic acid 102 and histidine 57 in the catalytic triad of serine proteases is an example of a catalytically important LBHB. Experimental facts are here considered regarding the aspartic acid-histidine and cis-urocanic H-bonds that are inconsistent with fundamental tenets of the LBHB hypothesis. The inconsistencies between theory and experiment in these paradigm systems cast doubt on the existence of LBHBs, as currently defined, within enzyme active sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ash, E L -- Sudmeier, J L -- De Fabo, E C -- Bachovchin, W W -- GM27927/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Nov 7;278(5340):1128-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Tufts University School of Medicine, Boston, MA 02111, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9353195" target="_blank"〉PubMed〈/a〉
    Keywords: Aspartic Acid/chemistry ; Binding Sites ; Boronic Acids/metabolism ; Catalysis ; Histidine/chemistry ; Hydrogen Bonding ; Hydrogen-Ion Concentration ; Magnetic Resonance Spectroscopy ; Oligopeptides/metabolism ; Protons ; Serine Endopeptidases/*chemistry/metabolism ; Serine Proteinase Inhibitors/metabolism ; Subtilisins/chemistry ; Temperature ; Urocanic Acid/chemistry
    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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  • 57
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-04-25
    Description: Transcription of c-myc in plasma cells, which are terminally differentiated B cells, is repressed by plasmacytoma repressor factor. This factor was identified as Blimp-1, known for its ability to induce B cell differentiation. Blimp-1 repressed c-myc promoter activity in a binding site-dependent manner. Treatment of BCL1 lymphoma cells with interleukin-2 (IL-2) plus IL-5 induced Blimp-1 and caused a subsequent decline in c-Myc protein. Ectopic expression of Blimp-1 in Abelson-transformed precursor B cells repressed endogenous c-Myc and caused apoptosis; Blimp-1-induced death was partially overcome by ectopic expression of c-Myc. Thus, repression of c-myc is a component of the Blimp-1 program of terminal B cell differentiation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lin, Y -- Wong, K -- Calame, K -- New York, N.Y. -- Science. 1997 Apr 25;276(5312):596-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, 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/9110979" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Apoptosis ; B-Lymphocytes/*cytology/metabolism ; Binding Sites ; Cell Differentiation ; Cell Line ; Gene Expression Regulation ; *Genes, myc ; Interleukin-2/pharmacology ; Interleukin-5/pharmacology ; Mice ; Mutagenesis, Site-Directed ; Plasmacytoma ; Promoter Regions, Genetic ; *Repressor Proteins ; Transcription Factors/genetics/*metabolism ; *Transcription, Genetic ; Transfection ; Tumor Cells, Cultured ; Zinc Fingers
    Print ISSN: 0036-8075
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  • 58
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-08-08
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gura, T -- New York, N.Y. -- Science. 1997 Aug 8;277(5327):768.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9273698" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Apoptosis ; Apoptosis Regulatory Proteins ; Binding Sites ; Databases, Factual ; GPI-Linked Proteins ; Humans ; Membrane Glycoproteins/*metabolism/therapeutic use ; Neoplasms/*metabolism/pathology ; Rats ; Receptors, TNF-Related Apoptosis-Inducing Ligand ; Receptors, Tumor Necrosis Factor/chemistry/*metabolism ; TNF-Related Apoptosis-Inducing Ligand ; Tumor Cells, Cultured ; Tumor Necrosis Factor Decoy Receptors ; Tumor Necrosis Factor-alpha/*metabolism/therapeutic use
    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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  • 59
    Publication Date: 1997-05-30
    Description: STAT (signal transducers and activators of transcription) proteins undergo cytokine-dependent phosphorylation on serine and tyrosine. STAT3, a transcription factor for acute phase response genes, was found to act as an adapter molecule in signal transduction from the type I interferon receptor. STAT3 bound to a conserved sequence in the cytoplasmic tail of the IFNAR1 chain of the receptor and underwent interferon-dependent tyrosine phosphorylation. The p85 regulatory subunit of phosphatidylinositol 3-kinase, which activates a series of serine kinases, bound to phosphorylated STAT3 and subsequently underwent tyrosine phosphorylation. Thus, STAT3 acts as an adapter to couple another signaling pathway to the interferon receptor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pfeffer, L M -- Mullersman, J E -- Pfeffer, S R -- Murti, A -- Shi, W -- Yang, C H -- New York, N.Y. -- Science. 1997 May 30;276(5317):1418-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9162009" target="_blank"〉PubMed〈/a〉
    Keywords: Acute-Phase Proteins/*genetics ; Amino Acid Sequence ; Androstadienes/pharmacology ; Animals ; Binding Sites ; COS Cells ; Cell Line ; Cloning, Molecular ; Conserved Sequence ; DNA-Binding Proteins/genetics/*metabolism ; Enzyme Inhibitors/pharmacology ; Membrane Proteins ; Molecular Sequence Data ; Phosphatidylinositol 3-Kinases ; Phosphorylation ; Phosphotransferases (Alcohol Group Acceptor)/antagonists & ; inhibitors/genetics/*metabolism ; Point Mutation ; Protein Binding ; Receptor, Interferon alpha-beta ; Receptors, Interferon/*metabolism ; Recombinant Fusion Proteins/genetics/metabolism ; STAT3 Transcription Factor ; Signal Transduction ; Trans-Activators/genetics/*metabolism ; Tyrosine/metabolism
    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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  • 60
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1997-02-07
    Description: Self-splicing group I introns, like other large catalytic RNAs, contain structural domains. Although the crystal structure of one of these domains has been determined by x-ray analysis, its connection to the other major domain that contains the guanosine-binding site has not been known. Site-directed mutagenesis and kinetic analysis of RNA splicing were used to identify a base triple in the conserved core of both a cyanobacterial (Anabaena) and a eukaryotic (Tetrahymena) group I intron. This long-range interaction connects a sequence adjacent to the guanosine-binding site with the domain implicated in coordinating the 5' splice site helix, and it thereby contributes to formation of the active site. The resulting five-strand junction, in which a short helix forms base triples with three separate strands in the Tetrahymena intron, reveals exceptionally dense packing of RNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tanner, M A -- Cech, T R -- GM28039/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1997 Feb 7;275(5301):847-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Colorado, Boulder, Colorado 80309-0215, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9012355" target="_blank"〉PubMed〈/a〉
    Keywords: Anabaena/genetics ; Animals ; Base Composition ; Binding Sites ; Guanosine/metabolism ; *Introns ; Mutagenesis, Site-Directed ; *Nucleic Acid Conformation ; RNA Splicing ; RNA, Bacterial/genetics ; RNA, Catalytic/*chemistry/genetics/metabolism ; RNA, Protozoan/genetics ; Tetrahymena/genetics
    Print ISSN: 0036-8075
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  • 61
    Publication Date: 1997-04-25
    Description: Telomerase is a ribonucleoprotein enzyme essential for the replication of chromosome termini in most eukaryotes. Telomerase RNA components have been identified from many organisms, but no protein component has been demonstrated to catalyze telomeric DNA extension. Telomerase was purified from Euplotes aediculatus, a ciliated protozoan, and one of its proteins was partially sequenced by nanoelectrospray tandem mass spectrometry. Cloning and sequence analysis of the corresponding gene revealed that this 123-kilodalton protein (p123) contains reverse transcriptase motifs. A yeast (Saccharomyces cerevisiae) homolog was found and subsequently identified as EST2 (ever shorter telomeres), deletion of which had independently been shown to produce telomere defects. Introduction of single amino acid substitutions within the reverse transcriptase motifs of Est2 protein led to telomere shortening and senescence in yeast, indicating that these motifs are important for catalysis of telomere elongation in vivo. In vitro telomeric DNA extension occurred with extracts from wild-type yeast but not from est2 mutants or mutants deficient in telomerase RNA. Thus, the reverse transcriptase protein fold, previously known to be involved in retroviral replication and retrotransposition, is essential for normal chromosome telomere replication in diverse eukaryotes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lingner, J -- Hughes, T R -- Shevchenko, A -- Mann, M -- Lundblad, V -- Cech, T R -- AG11728/AG/NIA NIH HHS/ -- New York, N.Y. -- Science. 1997 Apr 25;276(5312):561-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9110970" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Catalysis ; Chromosomes/metabolism ; DNA, Fungal/metabolism ; DNA-Binding Proteins ; Euplotes/*enzymology ; Evolution, Molecular ; Fungal Proteins/chemistry/metabolism ; Genes, Fungal ; Genes, Protozoan ; Molecular Sequence Data ; Protein Conformation ; *Rna ; RNA, Fungal/metabolism ; RNA, Protozoan/metabolism ; RNA-Directed DNA Polymerase/*chemistry/metabolism ; Saccharomyces cerevisiae/enzymology ; Saccharomyces cerevisiae Proteins ; Sequence Alignment ; Telomerase/*chemistry/genetics/isolation & purification/metabolism ; Telomere/metabolism ; Templates, Genetic
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 62
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    Journal of Computational Chemistry 11 (1990) 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
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  • 63
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    Journal of Computational Chemistry 11 (1990), S. 1-18 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Counterpoise corrected ab initio calculations are reported for (H2O)2 and H2O-H2CO. Geometry searches were done in the moment-optimized basis DZP' at the SCF, MP2, and CEPA-1 levels of theory, followed by more accurate single-point calculations in basis ESPB, which includes bondfunctions to saturate the dispersion energy. The final equilibrium binding energies obtained are -4.7 ±0.3 kcal/mol for a near-linear (H2O)2 structure and -4.6 ±0.3 kcal/mol for a strongly bent HOH ‥ OCH2 structure. The energy difference between these systems is much smaller than in all previous ab initio work. Cyclic (C2h) and bifurcated (C2v) transition structures for (H2O)2 are located at 1.0 ±0.1 kcal/mol and 1.9 ±0.3 kcal/mol above the global minimum, respectively. A new partitioning scheme is presented that rigorously partitions the MP2 correlation interaction energy in intra and intermolecular (dispersion) contributions. These terms are large (up to 2 kcal/mol) but of opposite sign for most geometries studied and hence their overall effect upon the final structures is relatively small. The relative merits of the MP2 and CEPA-1 approaches are discussed are discussed and it is concluded that for economical reasons MP2 is to be preferred, especially for larger systems.
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  • 64
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    Journal of Computational Chemistry 11 (1990), S. 45-57 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A data compression method is presented that is generally applicable to first-order convergent iterative procedures that employ subspace expansions or extrapolations based on successive correction vectors. This method is based on the truncation of insignificant information in successive correction vectors. Although the correction vectors themselves may be severely truncated with the proposed approach, the final solution vector may be represented to arbitrary accuracy. A feature of the proposed method is that more slowly convergent iterative procedures allow the correction vectors to be more severely truncated without affecting the overall convergence rate. The method is implemented and applied to the iterative Davidson diagonalization method. If the compressed representation of the expansion vectors can be held in main computer memory, then a significant reduction in the I/O requirements is achieved.
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  • 65
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    Journal of Computational Chemistry 11 (1990), S. 67-75 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: By examining the displacement coordinate metric three modes of constrained optimization for large molecules and clusters are suggested. The first method corresponds to a conventional optimization using internal coordinates. The second mode has applications with respect to both internal and cartesian coordinates. The final mode is particularly interesting because it can result in computational savings. A mixture of both internal and cartesian coordinates is specified where these coordinates are usually a subset of the molecules or clusters total coordinate set. In the optimization only a subset of the energy derivatives need be evaluated reducing the computational effort associated with the gradient calculation.
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  • 66
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    Journal of Computational Chemistry 11 (1990), S. 82-87 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A finite-field method for the calculation of polarizabilities and hyperpolarizabilities is developed based on both an energy expansion and a dipole moment expansion. This procedure is implemented in the MOPAC semiempirical program. Values and components of the dipole moment (μ), polarizability (α), first hyperpolarizability (β), and second hyperpolarizability (γ) are calculated as an extension of the usual MOPAC run. Applications to benzene and substituted benzenes are shown as test cases utilizing both MNDO and AM1 Hamiltonians.
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  • 67
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    Journal of Computational Chemistry 11 (1990), S. 121-151 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A procedure has been developed for global energy minimization of surface loops of proteins in the presence of a fixed core. The ECEPP potential function has been modified to allow more accurate representations of hydrogen bond interactions and intrinsic torsional energies. A computationally efficient representation of hydration free energy has been introduced. A local minimization procedure has been developed that uses a cutoff distance, minimization with respect to subsets of degrees of freedom, analytical second derivatives, and distance constraints between rigid segments to achieve efficiency in applications to surface loops. Efficient procedures have been developed for deforming segments of the initial backbone structure and for removing overlaps. Global energy minimization of a surface loop is accomplished by generating a sequence (or a trajectory) of local minima, the component steps of which are generated by searching collections of local minima obtained by deforming seven-residue segments of the surface loop. The search at each component step consists of the following calculations: (1) A large collection of backbone structures is generated by deforming a seven-residue segment of the initial backbone structure. (2) A collection of low-energy backbone structures is generated by applying local energy minimization to the resulting collection of backbone structures (interactions involving side chains that will be searched in this component step are not included in the energy). (3) One low-energy side-chain structure is generated for each of the resulting low-energy backbone structures. (4) A collection of low-energy local minima is generated by applying local energy minimization to the resulting collection of structures. (5) The local minimum with the lowest energy is retained as the next point of the trajectory. Applications of our global search procedure to surface segments of bovine pancreatic trypsin inhibitor (BPTI) and bovine trypsin suggest that component-step searches are reasonably complete. The computational efficiency of component-step searches is such that trajectories consisting of about 10 component steps are feasible using an FPS-5200 array processor. Our procedure for global energy minimization of surface loops is being used to identify and correct problems with the potential function and to calculate protein structure using a combination of sequence homology and global energy minimization.
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  • 68
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    Journal of Computational Chemistry 11 (1990), S. 416-430 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A systematic analysis of the molecular electrostatic potential (MEP) is presented. This study has been performed with a twofold purpose: first, to study the MEP dependence with regard to the quality of the basis set used to compute the ab initio SCF wavefunction and second, to develop and to assess a new strategy for computing isoelectrostatic potential maps using the semiempirical MNDO wavefunction. The only differences between this procedure and the ab initio SCF MEP computation lie in the freezing of the inner electrons and in the origin of the first-order density matrix. The statistical analysis of MEPs computed for a large number of molecules from MNDO wavefunction and ab initio SCF wavefunctions obtained using STO-3G, 4-31G, 6-31G, 4-31G*, 6-31G*, and 6-31G** basis sets points out the ability of any wavefunction to reproduce the general topological characteristics of the MEP surfaces. Nevertheless, split-valence basis sets including polarization functions are necessary to obtain accurate MEP minimum energy values. MNDO wavefunction tends to overestimate the MEP minima depth by a constant factor and shows an excellent ability to reflect the relative variation of MEP minima energies derived from a rather sophisticated (6-31G*) basis set, lacking of the shortcomings detected in the semiempirical CNDO approximation.
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  • 69
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    Journal of Computational Chemistry 11 (1990), S. 487-492 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Expressions are derived for computing the kinetic energy of a peptide with fixed geometry, in terms of dihedral angles as generalized coordinates; other expressions required for the solution of Lagrange's equations are also presented. The peptide is regarded as held stationary at one end. We also outline the computations that are needed in calculating the components of the third derivative of a potential energy function that consists of a sum of pairwise interatomic interactions.
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  • 70
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    Journal of Computational Chemistry 11 (1990), S. 819-828 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Complexes of alkali and alkaline earth cations with organic compounds are modeled by describing ionligand interaction energies with pair potentials and intraligand as well as interligand energies with the MM2 potential. New pair potentials for the interaction of Li+, Na+, K+, Mg2+, and Ca2+ ions are derived on the basis of 30,000 ab initio interaction energy values with 70 selected model ligand molecules. Various problems of the combination of these two basically different potentials are discussed. An application for the K+ complex of 18-crown-6 is presented. For more flexible ligands the introduction of three-body correction terms of the pair potentials seems necessary.
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  • 71
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    Journal of Computational Chemistry 11 (1990), S. 924-929 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The geometry, electronic structure, and photoelectron spectra of Sb2 and Sb4 have been investigated employing the LCGTO-MP-LSD method. For both molecules the geometrical and spectroscopic constants computed using the VWN potential are in very good agreement with the available experimental data. The HeI photoelectron spectra were computed with different potentials (Xα, GL, HL, BH, and VWN). The calculated spectra are in excellent agreement with the experimental ones and the use of the VWN potential gives the most accurate results. The reliable results for molecules complement those for the Sb atom and show that the proposed LSD Model Potential is able to give an accurate description of the structural and spectroscopic properties of the title molecules.
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  • 72
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    Journal of Computational Chemistry 11 (1990), S. 958-971 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Intermolecular potential functions have been developed for use in computer simulations of alkyl ethers. The simple OPLS model was adopted and parameterized to yield good descriptions of bimolecular and ion-molecule complexes as well as to reproduce experimental thermodynamic properties of liquid ethers. The principal testing featured Monte Carlo statistical mechanics simulations for liquid dimethyl ether (DME), ethyl methyl ether (EME), diethyl ether (DEE), and tetrahydrofuran (THF). Average errors of 1-3% are obtained for the computed densities and heats of vaporization including results for THF at pressures up to 5000 atm. The torsional motion about the central C—O bonds in EME and DEE was included in the simulations using rotational potential functions fit to results of molecular mechanics (MM2) calculations. The liquid-state environment is found to have negligible effect on the conformational equilibria.
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  • 73
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    Journal of Computational Chemistry 11 (1990), S. 972-977 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A quadrature-point-driven implementation of the standard Rys polynomial method for computing two-electron repulsion integrals of gaussian basis functions has been found to be both concise and openended with respect to the angular momentum of the gaussian functions (i.e., s,p,d,f,g,…). These are important features in certain applications, such as molecular properties and property gradients.
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  • 74
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    Journal of Computational Chemistry 11 (1990), S. 994-1002 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Free energy perturbation calculations were performed to determine the free energy of binding associated with the presence of perhaps an unusual hydroxyl group in the transition state analog of nebularine, an inhibitor of the enzyme adenosine deaminase. The presence of a single hydroxyl group in this inhibitor has been found to contribute -9.8 kcal/mol to the free energy of binding, with a 108-fold increase in the binding affinity by the enzyme. In this work, we calculate the difference in solvation free energy for the 1,6-dihydropurine complex versus that of the 6-hydroxyl-1,6-dihydropurine complex to determine if this marked increase in binding affinity is attributed to an unusually hydrophobic hydroxyl group. The calculated ΔG associated for the solvation free energy is -11.8 kcal/mol. This large change in the solvation free energy suggests that this hydroxyl is instead unusually hydrophilic and that the difference in free energy of interaction for the two inhibitors to the enzyme must be at least ca. 20 kcal/mol. Although the crystal structure for adenosine deaminase is currently not known, we attempt to mimic the nature of the active site by constructing models which simulate the enzyme-inhibitor complex. We present a first attempt at determining the change in free energy of binding for a system in which structural data for the enzyme is incomplete. To do this, we construct what we believe is a minimal model of the binding between adenosine deaminase and an inhibitor. The active site is simulated as a single charged carboxyl group which can form a hydrogen bond with the hydroxyl group of the analog. Two different carboxyl anion models are used. In the first model, the association is modeled between an acetic acid anion and the modified inhibitor. The second model consists of a hydrophobic amino acid pocket with an interior Glu residue in the active site. From these models we calculate the change in free energy of association and the overall change in free energy of binding. We calculate the free energies of interaction both in the absence and presence of water. We conclude from this that the presence of a single suitably placed-CO-2 group probably cannot explain the binding effect of the-OH group and that additional interactions will be found in the adenosine deaminase active site.
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  • 75
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    Journal of Computational Chemistry 11 (1990), S. 1029-1037 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Pseudopotentials and valence basis sets to be used in calculations for organometallic compounds of zinc and magnesium have been tested in calculations for the M(CH3)n (M = Zn, Mg; n = 1,2) molecules. Valence correlation effects are treated at the SDCI and CEPA levels. The capability of a polarization potential on zinc to account for the valence shell contracting effect of core valence correlation is studied. Properties considered are geometries, force constants, Mulliken populations, ionization potentials, atomization, and binding energies. Differences in bonding between the two dimethyl compounds are discussed.
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  • 76
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    Journal of Computational Chemistry 11 (1990), S. 1094-1100 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The acid-catalyzed hydrolysis mechanisms of maleamic (4-amino-4-oxo-2-butenoic) acids were studied using AM1 method. The reaction proceeded mainly in two steps: (1) nucleophilic attack of the undissociated carboxyl group on the adjacent aminocarbonyl carbon via a zwitterionic intermediate; and (2) the rate-determining proton transfer to form the zwitterionic tetrahedral intermediate. In each step, the hydration of water and hydronium ion molecules was important in stabilizing the polarized intermediates. The substituent effects at the amide moiety and the 2,3-positions of the maleamic acids were qualitatively estimated for each step.
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    Journal of Computational Chemistry 11 (1990) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 78
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    Journal of Computational Chemistry 11 (1990), S. 1139-1146 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A prescription for applying the method of molecular similarity calculations based on electrostatic potentials and fields is developed by consideration of a typical structure-activity series. Firm conclusions are drawn about the nature of the grid of points surrounding the molecules and about the choice of geometry, but options for point charges are less clearcut.
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  • 79
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    Journal of Computational Chemistry 11 (1990), S. 899-908 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An expanded form of the Wiener number is suggested for characterization of molecular graphs and structure-property correlations. The simple, computer-oriented method for counting of the novel index is briefly discussed.
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  • 80
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    Journal of Computational Chemistry 11 (1990), S. 1193-1205 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A common requirement in conformational analysis is the identification of a molecule's lowest energy conformations. The application of the A* algorithm to this problem is examined. The algorithm uses heuristic information about the problem domain to direct the search and has been implemented in a system for performing automated conformational analysis. The method is detailed and sample results presented. Some limitations of the approach are identified.
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  • 81
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    Journal of Computational Chemistry 11 (1990), S. 1009-1016 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Heats of formation and net atomic charges of some 120 structures involving substituted phenols, anilines, and benzoic acids and the corresponding anions were calculated by MNDO, AM1, and PM3 semiempirical methods. The gas phase acidities of substituted phenols and anilines and the net atomic charges on the anionic heteroatoms of the corresponding anions have been successfully correlated with σ- constants. Moreover, good correlations with σ were found for the charges on the acidic hydrogens of substituted phenols and anilines. In contrast, the gas phase acidities of substituted benzoic acids and the charges on the anionic oxygens of the corresponding anions are better correlated with Taft σ° constants. Comparisons of these results with experimental data and ab initio theoretical calculations indicate that AM1 and PM3 methods are much better than MNDO in predicting the acidity of aromatic compounds.
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  • 82
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    Journal of Computational Chemistry 11 (1990), S. 1038-1046 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We studied geometries and energies of complexes between water and neutral or protonated imidazole by ab initio molecular orbital calculations using the 4-31G basis set with and without the counterpoise correction. Positions of hydration sites and relative binding energies could be also estimated by using the electrostatic field map of imidazole as calculated by our bond increment method. The reliability of the calculations is confirmed by comparing the geometries of the imidazole-water complex to the experimental ones from the Cambridge Structural Database. These were obtained by X-ray diffraction studies on crystals with water bound to a molecule containing the imidazole fragment.
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  • 83
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    Journal of Computational Chemistry 11 (1990), S. 1061-1071 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for the evaluation of metal complexes with molecular mechanics calculations is described. The method has been employed to determine the global minimum energy conformations of three seven-coordinate lanthanide complexes. The method searches the potential energy surface of the metal complexes for the global minimum structure using the recently reported Random Incremental Pulse Search (RIPS). The molecular mechanics calculations were performed using the MM2 metal-extended force field (MM2MX). This force field excludes 1-3 bending terms about the metal center and, instead, explicitly includes 1-3 nonbonded van der Waals interactions. This affords a model based mainly on steric interactions about the ligating atoms, and removes the necessity of specifying ligand-metal-ligand bond angles for seven-coordinate and higher metal complexes in which no preferred bond angle can be proficiently determined. The calculated minimum-energy structures were well known seven-coordinate conformations in all cases, and a comparison with X-ray crystallographic is presented.
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  • 84
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    Journal of Computational Chemistry 11 (1990), S. 1076-1079 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The method of approximation of the frozen molecular fragment (FMF) we derived has been applied to calculations of proton affinities. Results are in good agreement with experimental data and extended basis set calculations.
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  • 85
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    Journal of Computational Chemistry 11 (1990), S. 1087-1093 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Myelin basic protein (MBP) is the major extrinsic protein of the myelin sheath in the central nervous system. It is this protein that is destroyed in such demyelinating diseases as multiple sclerosis. We have examined the predicted structures of one segment of MBP using the molecular mechanics program ECEPP83 developed by Scheraga and co-workers as modified by Chuman, Momany, and Schafer. We have focused upon a segment, 87-118, containing the Pro-Pro-Pro sequence (residues 100-102), which has been predicted from standard algorithms to exist in a hairpin loop connecting anti-parallel beta-strands. Several local energy minima have been found and reported. Tripoline sequences are not rare in proteins, but their structure and function is still uncertain.
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  • 86
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    Journal of Computational Chemistry 11 (1990), S. 1101-1110 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Two new computational methods for the evaluation and partitioning of projected, planar, and averaged slab electron densities, implemented in the program PRODEN, are presented. The new algorithms for the projection, demarcation, and integration of electron densities are described and evaluated in terms of speed and numerical accuracy. Integrated Projected Populations are analyzed and some of the advantages and limitations of the methods are discussed.
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  • 87
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    Journal of Computational Chemistry 11 (1990), S. 930-942 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The effect of the addition of diffuse functions of sp type on the first row atoms (and/or of d type on phosphorus) to a MINI-1 minimal basis set is evaluated by comparing the SCF description of the interaction energy and its decomposition, counterpoise (CP) corrected and uncorrected for basis set superposition errors (BSSEs), with that produced by extended basis sets (6-31G** and 3-21G+) as well as by basis sets (6-31G** + VPS and (2d)S), previously successfully tested, designed to minimize the BSSE. The systems considered are a few anions (F-, HCOO-, H2PO-4) H-bonded to water; the basis set performance on a different geometry (bifurcated instead of linear) of the phosphate-water adduct was also considered. An additional comparison with the interaction energy in a neutral dimer, (HF)2, was carried out. The addition of diffuse functions to the MINI-1 basis set, instead of resorting to extended basis sets, seems to be a sensible choice for anions. The equilibrium distance is shifted towards the reference basis set value at the CP corrected level as well as at the uncorrected one. The spread of the energy due to the basis set is hardly distinguishable when the CP corrected values are plotted. The description of the interaction energy in dimers involving phosphorus is improved using d type diffuse functions.
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  • 88
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    Journal of Computational Chemistry 11 (1990) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
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  • 89
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    Journal of Computational Chemistry 11 (1990), S. 1017-1020 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio CI calculations using pseudopotentials to describe germanium inner electrons are carried out on the low-lying excited singlet states (T2) of GeH4. A theoretical analysis of these states in terms of Mulliken population of Rydberg orbitals for each state and oscillator strengths allow us to reinterpret its experimental Vacuum UV electronic spectrum.
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  • 90
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    Journal of Computational Chemistry 11 (1990), S. 1047-1060 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The algorithm used by the program GEPOL to compute the Molecular Surface (MS), as defined by Richards, is presented in detail. GEPOL starts like other algorithms from a set of spheres with van der Waals radii, centered on the atoms or group of atoms of the molecule. GEPOL computes the MS by first searching the spaces inaccessible to the solvent and consequently filling them with a new set of spheres. Here we study the behavior of the method with its parameters, presenting several examples of application.
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  • 91
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    Journal of Computational Chemistry 11 (1990), S. 1080-1086 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A boundary element method is developed to compute the electrostatic potential inside and around molecules in an electrolyte solution. A set of boundary integral equations are derived based on the integral formulations of the Poisson equation and the linearized Poisson-Boltzmann equation. The boundary integral equations are then solved numerically after discretizing the molecular surface into a number of flat triangular elements. The method is applied to a spherical molecule for which analytical solutions are available. Use is made of both constant and linearly varying unknowns over the boundary elements, and the method is tested for various values of parameters such as the dielectric constant of the molecule, ionic strength, and the location of the interior point charge. The use of the boundary integral method incorporating the nonlinear Poisson-Boltzmann equation is also briefly discussed.
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  • 92
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    Journal of Computational Chemistry 11 (1990), S. 105-111 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A universal computational approach for evaluating integrals over gaussian basis functions for general operators of the form \documentclass{article}\pagestyle{empty}\begin{document}$$x^{k_x } y^{k_y } z^{k_z } \{ (\frac{\partial }{{\partial x'}})^{l_x } (\frac{\partial }{{\partial y'}})^{l_y } (\frac{\partial }{{\partial z'}})^{l_z } \frac{1}{{r'}}\} (\frac{\partial }{{\partial x}})^{m_x } (\frac{\partial }{{\partial y}})^{m_y } (\frac{\partial }{{\partial z'}})^{m_z } x^{n_x } y^{n_y } z^{n_z }$$\end{document} is presented. The implementation is open-ended with respect to the types of basis functions (s, p, d, f, g, h…) and with respect to the integers that specify the operator. These one-electron integrals comprise operators associated with electrical and magnetic properties of molecules and include those needed to find multipole polarizabilities, multipole susceptibilities, chemical shifts, and so on. The scheme also generates the usual kinetic, nuclear attraction, and overlap operators.
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  • 93
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    Journal of Computational Chemistry 11 (1990), S. 181-193 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A general computational scheme for the rational design of chiral stationary phases for the chromatographic separation of enantiomers has been established. The developed scheme was based on applying different interaction models (force field methods versus semi empirical quantum chemical methods), different docking algorithms (systematic grid search methods versus interactive methods guided by rules based on binding modes) and different levels of approximations (rigid versus flexible docking) to a representative test problem containing the 3,5-dinitrobenzoyl group. The computational methods in use covered the most sophisticated methods which could presently be applied to problems of such a size (about 80 atoms). It has been shown that the current computational approaches using rigid body approximations for the docked molecules and simple molecular mechanics (not taking pi-“effects” into account) are invalid in view of the required predictive precision of about 1-2 Kcal/mole for the differential binding energy. Another surprising result was the failure of the commonly used systematic search methods in determining the most favorable binding modes. Based on our calculations on the representative test problem we propose a new arrangement for the most stable complexes without parallel stacking of the aromatic pi-donor and the 3,5-dinitrobenzoyl pi-acceptor systems.
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    Journal of Computational Chemistry 11 (1990), S. 223-235 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A novel efficient computer-oriented approach, based on the DAST (dualist angle-restricted spanning tree) code, is introduced for enumeration and generation of planar polyhex hydrocarbons. It is much faster than other approaches in the literature. The numbers of planar polyhex hydrocarbons with 14 hexagons are reported for the first time.
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  • 95
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    Journal of Computational Chemistry 11 (1990), S. 242-248 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Variations of a procedure have been examined for minimization of the energies, calculated using MM2, of two docked molecules. After doing the intramolecular minimization of the individual molecules, randomized orientations of the rigid molecules were brought together to form complexes and the nonbonded energies of interaction were then minimized. Next, pairs having energies within 4.0 kcal/mol of the most stable pair were minimized further by atom-by-atom relaxation of the complex. Only two repetitions of the last two steps were found to give values within 0.001 kcal/mol in more than 90% of the cases. Compared to two other variations of the procedure, this method appeared to avoid erroneous (local, not global) minima. Finally, this overall procedure was tested against chromatographic data in the literature. Using only the most stable comformer of each species, the results appeared to be in qualitative agreement with fractionation data for enantiomeric aminoethanes on a chiral packing very similar to the one modeled here.
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  • 96
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    Journal of Computational Chemistry 11 (1990), S. 249-264 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Structural optimizations of the apically substituted isomer of PH4O- and the diapically substituted isomer of PH3FO- with diffuse-function augmented 3-21G* basis sets and with the 6-31 + G* and 6-31 + + G* basis sets result in P-η4-coordination in these anions. The structures obtained are those of a hydride or fluoride ion “solvated” by or complexed with phosphine oxide, rather than phosphoranes. In contrast, 3-21G* basis sets without diffuse functions on the atom in the trans-apical position with regard to the oxy-substituent yield P-η5-phosphorane structures that appear to be computational artifacts of the small basis set; the formation of the P-η4-geometries is curtailed by the insufficient functional description of the potential trans-apical nucleophilic leaving group. The overall neutral apical isomers of PH4O- · E(E = Li+, NH4+), the diapical isomer of PH3FO-Li+, as well as the model-solvated apical isomer of PH4O- · HF favor P-η5-phosphorane geometries at all of these computational levels. The mechanism by which the E-group alters the electronic structures within PH4Oa- is discussed based on the geometries, the molecular orbitals, and electron density analysis techniques.
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  • 97
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    Journal of Computational Chemistry 11 (1990), S. 291-296 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The adsorption of methane, ethane, propane, n-butane, ethylene, propene, 1-butene, 1,3-butadiene, acetylene, benzene, toluene, naphthalene, anthracene, and pyrene on the basal plane of graphite has been studied by means of a semiempirical method proposed by Fraga based on a 1/R expansion of atom-atom pair potentials. The energies of interaction obtained agree reasonably well with experimental data and statistical calculations. The orientation of the adsorbed molecules relative to the graphite surface rendered by Fraga's method improves the picture provided by other calculations with empirical potentials. These results display Fraga's method as an economical alternative for the study of physisorption of hydrocarbons on the graphite surface.
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  • 98
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    Journal of Computational Chemistry 11 (1990), S. 311-313 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A common approximation used in ab initio molecular orbital calculations assumes that the changes in energy due to use of a larger basis set (as in the inclusion of polarization orbitals) and to allowance for electron correlation are additives. Thus, small basis sets may be used for correlated ab initio calculations, resulting in a great savings in time. While this approach has been shown to perform acceptably in some cases, a systematic study has not been published. We examined 35 species and computed the heats of reaction for 15 processes at the 6-31G level of theory using polarization and correlation correction up to the MP4 level. The same items were then treated by an additive procedure to attain the same level of theory. We also examined the conrotrary ring opening of cyclobutene. Our results indicate that the errors do cancel to some extent but that the uncertainty associated with open shell species is significantly larger than closed shell systems. This calls into question the use of the procedure in predicting the properties of transition states.
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  • 99
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    Journal of Computational Chemistry 11 (1990), S. 336-345 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Simplified formulas for first and second derivatives of the internal coordinates with respect to Cartesian coordinates are reported for linear and out-of-plane bending motion. They are expressed in a local coordinate system and then rotated to a space-fixed Cartesian coordinate system. For linear motion the important points are: (1) the invariance of the energy with respect to translational and rotational coordinate transformations and (2) the presentation of derivatives of the energy in terms of (α - π)2 rather than (α - π), where α is the bond angle, to avoid indeterminant forms. By factoring the second derivatives of the energy with respect to (α - π) and sinα, analysis in this local coordinate system avoids division by sinα as α → π. The formulas describe linear systems without the need to project the motion onto two perpendicular planes. When the angle is exactly π two degenerate directions arise, and the coordinate axes perpendicular to the axis of the linear sequence of atoms may be chosen arbitrarily. Further refinements and clarifications of methods reported previously to obtain matrix elements for linear and out-of-plane motion are presented.
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    Journal of Computational Chemistry 11 (1990), S. 382-395 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The coefficients in power series, in the variable time, describing coupled nonlinear chemical reactions are easily obtained from a recursion relation. Since these series have a limited radius of convergence they are not very useful as such. If the series are inverted to give time as a function of the appropriate power of a progress variable, the new series converge over the entire time course of the reaction. If, further, the long-time asymptotic behavior, obtained from the linearized kinetic equations, is used, one can obtain a series expansion for a function that describes the correct short-time behavior. This function can be estimated very well using truncated series. The method works well for consecutive nonlinear reactions where the progress variables are monotonic functions of time; this includes many cases where the concentrations of intermediate species go through a maximum as the reaction progresses.
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