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Regulation of Pyruvate Dehydrogenase Kinase Activity by Protein Thiol-Disulfide Exchange
Flora H. Pettit, Jean Humphreys and Lester J. Reed
Proceedings of the National Academy of Sciences of the United States of America
Vol. 79, No. 13, [Part 1: Biological Sciences] (Jul. 1, 1982), pp. 3945-3948
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/12351
Page Count: 4
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Endogenous kinase activity of highly purified pyruvate dehydrogenase complex from bovine kidney is markedly inhibited by N-ethylmaleimide and by certain disulfides. Inhibition by disulfides is highly specific and is reversed by thiols. 5,5′-Dithiobis(2-nitrobenzoate) is the most potent inhibitor, showing significant inhibition at a concentration as low as 1 μ M. Cystamine, oxidized glutathione, pantethine, lipoic acid, lipoamide, ergothionine, insulin, oxytocin, and vasopressin were ineffective. Hydrogen peroxide and t-butyl hydroperoxide were inactive. The data indicate pyruvate dehydrogenase kinase (EC 18.104.22.168) contains a thiol group (or groups) that is involved in maintaining a conformation of the enzyme that facilitates phosphorylation and inactivation of its protein substrate, pyruvate dehydrogenase (EC 22.214.171.124). These findings suggest that modulation of pyruvate dehydrogenase kinase activity by thiol-disulfide exchange may be an important physiological mechanism for regulation of kinase activity and, hence, activity of the pyruvate dehydrogenase complex.
Proceedings of the National Academy of Sciences of the United States of America © 1982 National Academy of Sciences