Source:http://linkedlifedata.com/resource/pubmed/id/15247244
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
39
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| pubmed:dateCreated |
2004-9-20
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| pubmed:abstractText |
Hydroxymethylglutaryl-CoA synthase-catalyzed condensation of acetyl-CoA with acetoacetyl-CoA requires enolization/carbanion formation from the acetyl C-2 methyl group prior to formation of a new carbon-carbon bond. Acetyldithio-CoA, a readily enolizable analog of acetyl-CoA, was an effective competitive inhibitor of avian hydroxymethylglutaryl-CoA synthase (Ki = 28 microm). In the absence of cosubstrate, enzyme catalyzed the enolization/proton exchange from the C-2 methyl group of acetyldithio-CoA. Mutant enzymes that exhibited impaired formation of the covalent acetyl-S-enzyme reaction intermediate exhibited diminished (D159A and D203A) or undetectable (C129S) rates of enolization of acetyldithio-CoA. The results suggest that covalent thioacetylation of protein, which has not been detected previously for other enzymes that enolize this analog, occurs with hydroxymethylglutaryl-CoA synthase. Enzyme catalyzed the transfer of the thioacetyl group of this analog to 3'-dephospho-CoA suggesting the intermediacy of a covalent thioacetyl-S-enzyme species, which appears to be important for proton abstraction from C-2 of the thioacetyl group. Avian enzyme glutamate 95 is crucial to substrate condensation to form a new carboncarbon bond. Mutations of this invariant residue (avian enzyme E95A and E95Q; Staphylococcus aureus enzyme E79Q) correlated with diminished ability to catalyze enolization of acetyldithio-CoA. Enolization by E95Q was not stimulated in the presence of acetoacetyl-CoA. These observations suggest either a direct (proton abstraction) or indirect (solvent polarization) role for this active site glutamate.
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| pubmed:grant | |
| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Acyl Coenzyme A,
http://linkedlifedata.com/resource/pubmed/chemical/Carbon,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Hydroxymethylglutaryl-CoA Synthase,
http://linkedlifedata.com/resource/pubmed/chemical/Protons,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/acetyldithio-coenzyme A
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| pubmed:status |
MEDLINE
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| pubmed:month |
Sep
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| pubmed:issn |
0021-9258
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| pubmed:author | |
| pubmed:copyrightInfo |
Copyright 2004 American Society for Biochemistry and Molecular Biology, Inc.
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| pubmed:issnType |
Print
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| pubmed:day |
24
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| pubmed:volume |
279
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
40283-8
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| pubmed:dateRevised |
2007-11-14
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| pubmed:meshHeading |
pubmed-meshheading:15247244-Acyl Coenzyme A,
pubmed-meshheading:15247244-Animals,
pubmed-meshheading:15247244-Binding Sites,
pubmed-meshheading:15247244-Biochemistry,
pubmed-meshheading:15247244-Birds,
pubmed-meshheading:15247244-Carbon,
pubmed-meshheading:15247244-Catalysis,
pubmed-meshheading:15247244-Dose-Response Relationship, Drug,
pubmed-meshheading:15247244-Glutamic Acid,
pubmed-meshheading:15247244-Hydrogen-Ion Concentration,
pubmed-meshheading:15247244-Hydroxymethylglutaryl-CoA Synthase,
pubmed-meshheading:15247244-Kinetics,
pubmed-meshheading:15247244-Models, Chemical,
pubmed-meshheading:15247244-Mutation,
pubmed-meshheading:15247244-Protein Binding,
pubmed-meshheading:15247244-Protons,
pubmed-meshheading:15247244-Recombinant Proteins,
pubmed-meshheading:15247244-Staphylococcus aureus,
pubmed-meshheading:15247244-Time Factors
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| pubmed:year |
2004
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| pubmed:articleTitle |
Utility of acetyldithio-CoA in detecting the influence of active site residues on substrate enolization by 3-hydroxyl-3-methylglutaryl-CoA synthase.
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| pubmed:affiliation |
Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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