Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
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Animals
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Catalysis
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Insulin / chemistry
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Keto Acids / chemistry*
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Ketone Oxidoreductases / chemistry*
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Mitochondria, Heart / enzymology
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Multienzyme Complexes / chemistry*
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NADP / chemistry
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Oxidation-Reduction
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Pyruvates / chemistry
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Pyruvic Acid
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Substrate Specificity
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Swine
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Thioredoxin-Disulfide Reductase / chemistry
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Thioredoxins / chemistry*
Substances
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Insulin
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Keto Acids
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Multienzyme Complexes
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Pyruvates
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Thioredoxins
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NADP
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Pyruvic Acid
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Ketone Oxidoreductases
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3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
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Thioredoxin-Disulfide Reductase