[Regulation of alpha-ketoglutarate dehydrogenase complex from pigeon breast muscle].
The activity of alpha-ketoglutarate dehydrogenase complex from pigeon breast muscle is controlled by ADP and the reaction products, i. e. succinyl-CoA and NADH. ADP activates the alpha-ketoglutarate dehydrogenase component of the complex, whereas NADH inhibits alpha-ketoglutarate dehydrogenase and lipoyl dehydrogenase. In the presence of NADH the kinetic curve of the complex with respect to alpha-ketoglutarate and NAD and the dependence of upsilon versus [NAD] and upsilon versus [Lip (SH)2] in the lipoyl dehydrogenase reaction are S-shaped. In the absence of inhibitor ADP had no activating effect on lipoyl dehydrogenase; however, in the presence of NADH ADP decreases the cooperativity for NAD. The cooperative kinetics of the constituent enzymes of the complex are indicative of its allosteric properties. Isolation of the alpha-ketoglutarate dehydrogenase complex and its lipoyl dehydrogenase and alpha-ketoglutarate dehydrogenase components in a desensitized state confirms their allosteric nature. It is assumed that NADH effects of isolated alpha-ketoglutarate dehydrogenase is due to a shift in the equilibrium between different oligomeric forms of the enzyme.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D010856:Columbidae; D007655:Ketoglutarate Dehydrogenase Complex / Q000378:metabolism*; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D009243:NAD / Q000494:pharmacology
D009243:NAD; D000244:Adenosine Diphosphate; D007658:Ketone Oxidoreductases; D007655:Ketoglutarate Dehydrogenase Complex
Reguliatsiia al'fa-ketoglutaratdegidrogenaznogo kompleksa iz grudnoĭ myshtsy golubia.