Document Detail

2-Oxo-3-alkynoic acids, universal mechanism-based inactivators of thiamin diphosphate-dependent decarboxylases: synthesis and evidence for potent inactivation of the pyruvate dehydrogenase multienzyme complex.
MedLine Citation:
PMID:  9201955     Owner:  NLM     Status:  MEDLINE    
A new class of compounds, the 2-oxo-3-alkynoic acids with a phenyl substituent at carbon 4 was reported by the authors as potent irreversible and mechanism-based inhibitors of the thiamin diphosphate- (ThDP-) dependent enzyme pyruvate decarboxylase [Chiu, C.-F., & Jordan, F. (1994) J. Org. Chem. 59, 5763-5766]. The method has been successfully extended to the synthesis of the 4-, 5-, and 7-carbon aliphatic members of this family of compounds. These three compounds were then tested on three ThDP-dependent pyruvate decarboxylases: the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc) and its E1 (ThDP-dependent) component, pyruvate oxidase (POX, phosphorylating; from Lactobacillus plantarum),and pyruvate decarboxylase (PDC) from Saccharomycescerevisiae. All three enzymes were irreversibly inhibited by the new compounds. The 4-carbon acid is the best substrate-analog inactivator known to date for PDHc, more potent than either fluoropyruvate or bromopyruvate. The following conclusions were drawn from extensive studies with PDHc: (a) The kinetics of inactivation of PDH complexes and of resolved E1 by 2-oxo-3-alkynoic acids is time- and concentration-dependent. (b) The 4-carbon acid has a Ki 2 orders of magnitude stronger than the 5-carbon acid, clearly demonstrating the substrate specificity of PDHc. (c) The rate of inactivation of PDH complexes and of resolved E1 by 2-oxo-3-alkynoic acids is enhanced by the addition of ThDP and MgCl2. (d) Pyruvate completely protects E1 and partially protects PDHc from inactivation by 2-oxo-3-butynoic acid. (e) E1 but not E2-E3 is the target of inactivation by 2-oxo-3-butynoic acid. (f) Inactivation of E1 by 2-oxo-3-butynoic acid is accompanied by modification of 1.3 cysteines/E1 monomer. The order of reactivity with the 4-carbon acid was PDHc > POX > PDC. While the order of reactivity with PDHc and POX was 2-oxo-3-butynoic acid > 2-oxo-3-pentynoic acid > 2-oxo-3-heptynoic acid, the order of reactivity was reversed with PDC.
A Brown; N Nemeria; J Yi; D Zhang; W B Jordan; R S Machado; J R Guest; F Jordan
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochemistry     Volume:  36     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-07-21     Completed Date:  1997-07-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  8071-81     Citation Subset:  IM    
Department of Chemistry, Rutgers, The State University of New Jersey, Newark, New Jersey 07102, USA.
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MeSH Terms
Bacterial Proteins / metabolism
Enzyme Activation
Escherichia coli / enzymology
Fatty Acids, Unsaturated / pharmacology*
Fungal Proteins / metabolism
Lactobacillus / enzymology
Pyruvate Decarboxylase / metabolism*
Pyruvate Dehydrogenase Complex / antagonists & inhibitors*,  biosynthesis,  metabolism*
Pyruvate Oxidase / metabolism*
Saccharomyces cerevisiae / enzymology
Thiamine Pyrophosphate / metabolism*
Grant Support
Reg. No./Substance:
0/Bacterial Proteins; 0/Fatty Acids, Unsaturated; 0/Fungal Proteins; 0/Pyruvate Dehydrogenase Complex; 154-87-0/Thiamine Pyrophosphate; 56842-75-2/2-keto-3-butynoic acid; EC Oxidase; EC Decarboxylase

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