Thioredoxin reduction dependent on alpha-ketoacid oxidation by alpha-ketoacid dehydrogenase complexes.
The pyruvate and alpha-ketoglutarate dehydrogenase complexes isolated from pig heart mitochondria promote the reduction of thioredoxin in the presence of their alpha-ketoacid substrates, coenzyme A, and free lipoate. Substrate-specific generation of reduced thioredoxin was established by two independent methods, viz. reduction of insulin and thioredoxin reductase-catalyzed NADPH formation. Dihydrolipoate accumulating in the absence of NAD+ is the likely intermediate. A redox function in alpha-ketoacid oxidation provides a potential role for the specific thioredoxins previously identified by us in mitochondria.
Bunik
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A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation.
Follmann
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D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D000818:Animals; D002384:Catalysis; D007328:Insulin / Q000737:chemistry; D007651:Keto Acids / Q000737:chemistry*; D007658:Ketone Oxidoreductases / Q000737:chemistry*; D008929:Mitochondria, Heart / Q000201:enzymology; D009097:Multienzyme Complexes / Q000737:chemistry*; D009249:NADP / Q000737:chemistry; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000737:chemistry; D019289:Pyruvic Acid; D013379:Substrate Specificity; D013552:Swine; D013880:Thioredoxin-Disulfide Reductase / Q000737:chemistry; D013879:Thioredoxins / Q000737:chemistry*
D007328:Insulin; D007651:Keto Acids; D009097:Multienzyme Complexes; D011773:Pyruvates; D013879:Thioredoxins; D009249:NADP; D019289:Pyruvic Acid; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D013880:Thioredoxin-Disulfide Reductase