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  • Articles  (3)
  • Data
  • Hydrogen-Ion Concentration  (3)
  • Chemistry
  • American Association for the Advancement of Science (AAAS)  (3)
  • 1
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    Observation of covalent intermediates in an enzyme mechanism at atomic resolution (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-10-13
    Description: In classical enzymology, intermediates and transition states in a catalytic mechanism are usually inferred from a series of biochemical experiments. Here, we derive an enzyme mechanism from true atomic-resolution x-ray structures of reaction intermediates. Two ultra-high resolution structures of wild-type and mutant d-2-deoxyribose-5-phosphate (DRP) aldolase complexes with DRP at 1.05 and 1.10 angstroms unambiguously identify the postulated covalent carbinolamine and Schiff base intermediates in the aldolase mechanism. In combination with site-directed mutagenesis and (1)H nuclear magnetic resonance, we can now propose how the heretofore elusive C-2 proton abstraction step and the overall stereochemical course are accomplished. A proton relay system appears to activate a conserved active-site water that functions as the critical mediator for proton transfer.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Heine, A -- DeSantis, G -- Luz, J G -- Mitchell, M -- Wong, C H -- Wilson, I A -- GM44154/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2001 Oct 12;294(5541):369-74.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11598300" target="_blank"〉PubMed〈/a〉
    Keywords: Aldehyde-Lyases/*chemistry/genetics/*metabolism ; Amino Acid Substitution ; Binding Sites ; Catalysis ; Chemistry, Physical ; Crystallization ; Crystallography, X-Ray ; Escherichia coli/enzymology ; Hydrogen Bonding ; Hydrogen-Ion Concentration ; Ligands ; Lysine/chemistry ; Models, Chemical ; Mutagenesis, Site-Directed ; Mutation ; Nuclear Magnetic Resonance, Biomolecular ; Physicochemical Phenomena ; Protein Conformation ; Protein Folding ; Protein Structure, Tertiary ; Protons ; Ribosemonophosphates/*chemistry/*metabolism ; Schiff Bases ; Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    An antibody exo Diels-Alderase inhibitor complex at 1.95 angstrom resolution (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1998-04-16
    Description: A highly specific Diels-Alder protein catalyst was made by manipulating the antibody repertoire of the immune system. The catalytic antibody 13G5 catalyzes a disfavored exo Diels-Alder transformation in a reaction for which there is no natural enzyme counterpart and that yields a single regioisomer in high enantiomeric excess. The crystal structure of the antibody Fab in complex with a ferrocenyl inhibitor containing the essential haptenic core that elicited 13G5 was determined at 1.95 angstrom resolution. Three key antibody residues appear to be responsible for the observed catalysis and product control. Tyrosine-L36 acts as a Lewis acid activating the dienophile for nucleophilic attack, and asparagine-L91 and aspartic acid-H50 form hydrogen bonds to the carboxylate side chain that substitutes for the carbamate diene substrate. This hydrogen-bonding scheme leads to rate acceleration and also pronounced stereoselectivity. Docking experiments with the four possible ortho transition states of the reaction explain the specific exo effect and suggest that the (3R,4R)-exo stereoisomer is the preferred product.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Heine, A -- Stura, E A -- Yli-Kauhaluoma, J T -- Gao, C -- Deng, Q -- Beno, B R -- Houk, K N -- Janda, K D -- Wilson, I A -- CA27489/CA/NCI NIH HHS/ -- GM-43858/GM/NIGMS NIH HHS/ -- P01 CA27489/CA/NCI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1998 Mar 20;279(5358):1934-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Skaggs Institute of Chemical 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/9506943" target="_blank"〉PubMed〈/a〉
    Keywords: Antibodies, Catalytic/*chemistry/immunology/metabolism ; Catalysis ; Chemistry, Organic ; Crystallography, X-Ray ; Ferrous Compounds/*chemistry/immunology/metabolism ; Haptens/chemistry/immunology ; Hydrogen Bonding ; Hydrogen-Ion Concentration ; Immunoglobulin Fab Fragments/chemistry ; Models, Molecular ; Organic Chemistry Phenomena ; Stereoisomerism ; Thermodynamics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Immune versus natural selection: antibody aldolases with enzymic rates but broader scope (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1998-02-12
    Description: Structural and mechanistic studies show that when the selection criteria of the immune system are changed, catalytic antibodies that have the efficiency of natural enzymes evolve, but the catalytic antibodies are much more accepting of a wide range of substrates. The catalytic antibodies were prepared by reactive immunization, a process whereby the selection criteria of the immune system are changed from simple binding to chemical reactivity. This process yielded aldolase catalytic antibodies that approximated the rate acceleration of the natural enzyme used in glycolysis. Unlike the natural enzyme, however, the antibody aldolases catalyzed a variety of aldol reactions and decarboxylations. The crystal structure of one of these antibodies identified the reactive lysine residue that was selected in the immunization process. This lysine is deeply buried in a hydrophobic pocket at the base of the binding site, thereby accounting for its perturbed pKa.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barbas, C F 3rd -- Heine, A -- Zhong, G -- Hoffmann, T -- Gramatikova, S -- Bjornestedt, R -- List, B -- Anderson, J -- Stura, E A -- Wilson, I A -- Lerner, R A -- CA27489/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1997 Dec 19;278(5346):2085-92.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Skaggs Institute for Chemical Biology and the Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9405338" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Catalytic/chemistry/immunology/*metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Decarboxylation ; *Evolution, Molecular ; Fructose-Bisphosphate Aldolase/chemistry/immunology/*metabolism ; Glycolysis ; Hydrogen-Ion Concentration ; Immunization ; Immunoglobulin Fab Fragments/chemistry/immunology/*metabolism ; Kinetics ; Lysine/chemistry/metabolism ; Mice ; Models, Molecular ; Protein Conformation ; Pyridoxal/metabolism ; Selection, Genetic ; Substrate Specificity
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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