Essential histidine residues of alpha-ketoglutarate dehydrogenase from pigeon breast muscle.
Modification of histidine residues of alpha-ketoglutarate dehydrogenase results in complete inactivation of the enzyme. The kinetic curves for histidine residues modification and for alpha-ketoglutarate dehydrogenase inactivation are biphasic. The rate constants for both processes show a good coincidence at two phases. The complete inactivation of the enzyme is due to modification of one histidine at each step of the reaction. At saturating concentrations of the substrate, alpha-ketoglutarate, the inactivating effect of the modifier is lowered; the cofactors, thiamine pyrophosphate and Mg2+, exert no protective effect.
D000818:Animals; D001665:Binding Sites; D010856:Columbidae; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology; D006639:Histidine; D007655:Ketoglutarate Dehydrogenase Complex / Q000378:metabolism*; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*
D006639:Histidine; D007658:Ketone Oxidoreductases; D007655:Ketoglutarate Dehydrogenase Complex; D004047:Diethyl Pyrocarbonate