title: Regulation of pyruvate dehydrogenase kinase activity by protein thiol-disulfide exchange.
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 microM. 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.
mesh_terms: D000818:Animals; D002417:Cattle; D004220:Disulfides / Q000494:pharmacology*; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D012969:Sodium Fluoride / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000494:pharmacology*
chemical_list: D004220:Disulfides; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D013438:Sulfhydryl Compounds; D012969:Sodium Fluoride; D004228:Dithionitrobenzoic Acid; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D005033:Ethylmaleimide