Clofibric acid, phenylpyruvate, and dichloroacetate inhibition of branched-chain α-ketoacid dehydrogenase kinase in vitro and in perfused rat heart

Ralph Paxton, Robert A. Harris

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Branched-chain α-ketoacid dehydrogenase kinase, purified from rabbit liver, was inhibited by clofibric acid, phenylpyruvate, and dichloroacetate in a mixed manner relative to ATP. I40 values relative to 75 μm ATP were 0.33, 1.7, and 3.0 mm, respectively. Inhibition of the kinase by acetate, pyruvate, and lactate was minimal; whereas a p-hydroxyphenyl substitution of these compounds increased their potency as kinase inhibitors, a phenyl substitution gave the most potent inhibitors. Clofibric acid, phenylpyruvate, and dichloroacetate activated branched-chain α-ketoacid dehydrogenase in perfused rat hearts. Perfusate concentrations that gave 50% activation (A50) were 0.1, 0.32, and 0.63 mm, respectively. A50 concentrations of clofibric acid and phenylpyruvate also increased flux (decarboxylation of α-keto[1-14C]isovalerate) through branched-chain α-ketoacid dehydrogenase in perfused rat heart. These findings suggest that, although clofibric acid and phenylpyruvate can inhibit substrate utilization by the branched-chain α-ketoacid dehydrogenase complex, the major effect of these compounds on branched-chain amino acid metabolism is due to inhibition of branched-chain α-ketoacid dehydrogenase kinase with subsequent activation of and increased flux through the complex.

Original languageEnglish (US)
Pages (from-to)58-66
Number of pages9
JournalArchives of Biochemistry and Biophysics
Volume231
Issue number1
DOIs
StatePublished - May 15 1984

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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