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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
Stable URL: http://www.jstor.org/stable/12351
Page Count: 4
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Regulation of Pyruvate Dehydrogenase Kinase Activity by Protein Thiol-Disulfide Exchange
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Abstract

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 2.7.1.99) 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 1.2.4.1). 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.

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