Document Detail


Interaction of 3,4-dienoyl-CoA thioesters with medium chain acyl-CoA dehydrogenase: stereochemistry of inactivation of a flavoenzyme.
MedLine Citation:
PMID:  11591145     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The medium chain acyl-CoA dehydrogenase is rapidly inhibited by racemic 3,4-dienoyl-CoA derivatives with a stoichiometry of two molecules of racemate per enzyme flavin. Synthesis of R- and S-3,4-decadienoyl-CoA shows that the R-enantiomer is a potent, stoichiometric, inhibitor of the enzyme. alpha-Proton abstraction yields an enolate to oxidized flavin charge-transfer intermediate prior to adduct formation. The crystal structure of the reduced, inactive enzyme shows a single covalent bond linking the C-4 carbon of the 2,4-dienoyl-CoA moiety and the N5 locus of reduced flavin. The kinetics of reversal of adduct formation by release of the conjugated 2,4-diene were evaluated as a function of both acyl chain length and truncation of the CoA moiety. The adduct is most stable with medium chain length allenic inhibitors. However, the adducts with R-3,4-decadienoyl-pantetheine and -N-acetylcysteamine are some 9- and >100-fold more kinetically stable than the full-length CoA thioester. Crystal structures of these reduced enzyme species, determined to 2.4 A, suggest that the placement of H-bonds to the inhibitor carbonyl oxygen and the positioning of the catalytic base are important determinants of adduct stability. The S-3,4-decadienoyl-CoA is not a significant inhibitor of the medium chain dehydrogenase and does not form a detectable flavin adduct. However, the S-isomer is rapidly isomerized to the trans-trans-2,4-conjugated diene. Protein modeling studies suggest that the S-enantiomer cannot approach close enough to the isoalloxazine ring to form a flavin adduct, but can be facilely reprotonated by the catalytic base. These studies show that truncation of CoA thioesters may allow the design of unexpectedly potent lipophilic inhibitors of fatty acid oxidation.
Authors:
W Wang; Z Fu; J Z Zhou; J J Kim; C Thorpe
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochemistry     Volume:  40     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  2001 Oct 
Date Detail:
Created Date:  2001-10-09     Completed Date:  2001-11-01     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  12266-75     Citation Subset:  IM    
Affiliation:
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
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MeSH Terms
Descriptor/Qualifier:
Acyl Coenzyme A / chemical synthesis,  chemistry,  pharmacology*
Acyl-CoA Dehydrogenase
Acyl-CoA Dehydrogenases / antagonists & inhibitors*,  chemistry
Animals
Catalytic Domain
Drug Stability
Enzyme Inhibitors / chemical synthesis,  chemistry,  pharmacology*
Kinetics
Models, Molecular
Protein Conformation
Spectrophotometry
Stereoisomerism
Structure-Activity Relationship
Swine
Grant Support
ID/Acronym/Agency:
GM26643/GM/NIGMS NIH HHS; GM29076/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Acyl Coenzyme A; 0/Enzyme Inhibitors; EC 1.3.-/Acyl-CoA Dehydrogenases; EC 1.3.99.3/Acyl-CoA Dehydrogenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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