title: The substrate-mediated inactivation of the pyruvate dehydrogenase component of the pigeon breast muscle pyruvate dehydrogenase complex.
abstract: Incubation of the pyruvate dehydrogenase component isolated from the pigeon breast muscle pyruvate dehydrogenase complex with Mg2+, thiamine pyrophosphate and low concentrations of pyruvic acid in the absence of electron acceptors results in irreversible time-dependent inactivation of the enzyme. The rate of the enzyme inactivation is markedly decreased in the presence of high concentrations of pyruvate; in this case acetoin and acetolactate are detected in the reaction mixture. The enzyme activity is stabilized when the artificial electron acceptor, 2,6-dichlorophenolindophenol, is present in the reaction mixture. The substrate-mediated inactivation of the enzyme is accompanied by incorporation of the 2-[14C]-substrate fragment and labelled thiamine pyrophosphate into the protein fraction. The enzyme reactivation by neutral hydroxylamine and the protective effect of dithiothreitol suggest that the SH-group(s) may be involved in the substrate-mediated inactivation of pyruvate dehydrogenase.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D010856:Columbidae; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D030481:Pyruvate Dehydrogenase (Lipoamide); D011768:Pyruvate Dehydrogenase Complex / Q000037:antagonists & inhibitors*; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D013835:Thiamine Pyrophosphate / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D011768:Pyruvate Dehydrogenase Complex; D011773:Pyruvates; D019289:Pyruvic Acid; D030481:Pyruvate Dehydrogenase (Lipoamide); D013835:Thiamine Pyrophosphate