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Horm Metab Res 1988; 20(6): 317-322
DOI: 10.1055/s-2007-1010826
ORIGINALS
Basic
© Georg Thieme Verlag, Stuttgart · New York

Branched Chain α-Ketoacid Dehydrogenase and Pyruvate Dehydrogenase Activity in Isolated Rat Pancreatic Islets

R. Paxton1 , R. A. Harris2 , A. Sener3 , W. J. Malaisse3
  • 1Department of Biological Sciences, Texas Tech University, Lubbock, Texas, U.S.A.
  • 2Department of Biochemistry, Indiana University School of Medicine, Indianapolis, U.S.A.
  • 3Laboratory of Experimental Medicine, University of Brussels, Brussels, Belgium
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Publication History

1987

1987

Publication Date:
14 March 2008 (online)

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Summary

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.

Key-Words

Branched-Chain α-Ketoacid Dehydrogenase - Pyruvate Dehydrogenase - Isolated Pancreatic Islets - Insulin Release - α-Ketoacids - α-Chloroisocaproate