Interaction of the membrane-bound succinate dehydrogenase with substrate and competitive inhibitors

Alexander Kotlyar, Andrei D. Vinogradov

Research output: Contribution to journalArticlepeer-review

Abstract

The protective effect of dicarboxylates on the active-site-directed inhibition of the membrane-bound succinate dehydrogenase by N-ethylmaleimide, steady-state kinetics methods for Ki and K, determinations, and equillibrium studies were employed to quantitate the relative the relative affinities of succinate, fumarate, malonate and oxaloacetate to the reduced and oxidixed species of the enzyme. A more than 10-fold difference in the relative affinities of the reduced and oxidized succinate dehydrogenase to succinate, fumarate and oxaloacetate is found, whereas the reactivity of the active-site sulphydryl group does not depend on the redox state of the enzyme. The redox-state-dependent changes in the affinity of the membrane-bound succinate dehydrogenase to oxaloacetate can be quantitatively accounted for by a 10-fold increase in the rate of dissociation of the enzyme-inhibitor complex whch occurs upon reduction of the enzyme. The data obtained give no support for either the existence of a sulphydryl group other than the active-site one important for the catalysis or for the presence of a separate dicarboxylate-specific regulatory site in the succinate dehydrogenase molecule.

Original languageEnglish
Pages (from-to)24-34
Number of pages11
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume784
Issue number1
DOIs
StatePublished - 18 Jan 1984
Externally publishedYes

Keywords

  • Redox state
  • Substrate affinity
  • Succinate dehydrogenase
  • Sulfhydryl group

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