Branched-chain α-ketoacid dehydrogenase and pyruvate Dehydrogenase in isolated rat pancreatic islets were shown to be regulated by a phosphorylation/dephosphorylation mechanism. Broad-specificity phosphoprotein phosphatase treatment stimulated and ATP addition inhibited their activities. The kinases responsible for inactivating these complexes were shown to be sensitive to inhibition by known inhibitors, α-chloroisocaproate and dichloroacetate. Total activity (nmol/min/islet @ 37°C) of branched-chain α-ketoacid dehydrogenase and pyruvate dehydrogenase was 0.86 and 5.09, with a % active form (activity before phosphatase treatment divided by activity after phosphatase treatment X 100) of 36% and 94%, respectively. Incubation of intact isolated islets with α-chloroisocaproate affected neither insulin release nor flux through branched-chain α-ketoacid dehydrogenase.
Branched-Chain α-Ketoacid Dehydrogenase
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Pyruvate Dehydrogenase
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Isolated Pancreatic Islets
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Insulin Release
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α-Ketoacids
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α-Chloroisocaproate
