Conjugated αketo acids as mechanism-based inactivators of brewer's yeast pyruvate decarboxylase electronic effects of substituents and detection of a long-lived intermediate

Frank Jordan, Joseph Adams, Bijan Farzami, Zbigniew H. Kudzin

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

A series of phenyl substituted E-4-phenyl-2-keto-3-butenoic acid derivatives were synthesized (p-Cl, m-Cl, P-NO2, m-NO2, o-NO2, 3,4-Cl2 2,6-Cl2, p-CH3O, P-(CH3)3N) and tested as potential irreversible inhibitors of brewer's yeast pyruvate decarboxylase (EC 4.1.1.1). All those derivatives with electron withdrawing substituents were found to be time-dependent inactivators of the enzyme, unlike the P-CH3O- and p-(CH3)2N derivatives. Detailed kinetic studies with the m-nitro derivative (the most potent inhibitor) indicated that this compound formed reversible complexes with the enzyme at two sites (supposed regulatory and catalytic with Ki values of 0.026 and 0.13 mM, respectively) prior to irreversible inactivation of the enzyme. In addition, concurrently with the inactivation, addition of the m-NO2 derivative to the enzyme produced a new VIS absorbance with λmax near 430 nm. This absorbance was attributed to the enzyme-bound enamine intermediate. The time course of formation and disappearance of the intermediate could be determined and provided detailed information about the mechanism of the enzyme.

Original languageEnglish (US)
Pages (from-to)139-149
Number of pages11
JournalJournal of Enzyme Inhibition and Medicinal Chemistry
Volume1
Issue number2
DOIs
StatePublished - Jan 1 1986

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Drug Discovery

Keywords

  • Enamine
  • Mechanism-based inactivator
  • Yeast pyruvate decarboxylase
  • αketo acids

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