Abstract
A heat- and acid-stable protein inhibitor of the [branched-chain alpha-keto acid dehydrogenase]-phosphatase was purified over 100,000-fold from extracts of bovine kidney mitochondria. The nearly homogeneous protein was recovered with a yield of 4-8%. The apparent molecular weight of the inhibitor is about 36,000. This protein is a noncompetitive inhibitor of the phosphatase, and the inhibitor constant (Ki) is about 0.13 nM. The inhibition was reversed 50% by about 1.3 mM Mg2+ and about 0.1 mM spermine. This protein inhibitor is different from the cytosolic protein phosphatase inhibitors 1 and 2.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
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Amino Acids, Branched-Chain / metabolism*
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Animals
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Cattle
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Enzyme Inhibitors / isolation & purification*
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Hot Temperature
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Ketone Oxidoreductases / metabolism*
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Kidney / enzymology
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Magnesium / pharmacology
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Mitochondria / enzymology*
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Molecular Weight
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Multienzyme Complexes / metabolism*
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Protein Kinase Inhibitors*
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Protein Kinases*
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Spermine / pharmacology
Substances
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Amino Acids, Branched-Chain
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Enzyme Inhibitors
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Multienzyme Complexes
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Protein Kinase Inhibitors
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Spermine
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Ketone Oxidoreductases
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3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
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Protein Kinases
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(3-methyl-2-oxobutanoate dehydrogenase (lipoamide)) kinase
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Magnesium