Inactivation of α-ketoglutarate dehydrogenase during oxidative decarboxylation of α-ketoadipic acid

Abstractα-Ketoglutarate dehydrogenase was inactivated irreversibly and completely during oxidation of α-ketoadipic acid. The inactivation was revealed both in the model system with ferricyanide and in the overall reaction catalyzed by the α-ketoglutarate dehydrogenase complex. Neither substrate depletion nor product accumulation induced the inactivation. The results obtained were compared with recent data on the enzyme inactivation during oxidation of α-ketoglutaric acid. The differences in the inactivation kinetics observed with the two substrates of the enzyme were analyzed. They seem not to reflect the different mechanisms of the inactivation, but, rather, depend on the changes in the rates of the individual stages of the process

Effect of α-ketoglutarate and its structural analogues on hysteretic properties of α-ketoglutarate dehydrogenase

AbstractThe burst of product accumulation during the KGD reaction was investigated. It has been shown not to be the obligatory feature of catalysis, but appears when increasing the enzyme saturation by KG. Structural analogues of KG and the SH-group modification suppress the initial burst without preventing catalysis. The results obtained are in favour of the existence of the regulatory site for binding KG and its structural analogues essential for hysteretic properties of KGD