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
-
Pyruvate Dehydrogenase
-
Isolated Pancreatic Islets
-
Insulin Release
-
α-Ketoacids
-
α-Chloroisocaproate
