title: Inactivation of 2-oxoglutarate dehydrogenase in rat liver mitochondria by its substrate and t-butyl hydroperoxide.
abstract: Ketoacid oxidation in rat liver mitochondria was very sensitive to t-butyl hydroperoxide (t-BuOOH). Furthermore, 2-oxoglutarate and pyruvate each enhanced t-BuOOH-induced oxidative stresses of mitochondria, such as oxidation of pyridine nucleotides and GSH, inhibition of respiration with the other NAD-linked substrates, and peroxidation of mitochondrial lipids. We provide evidence that the t-BuOOH and ketoacid-induced effects are due to the failure of supply of NADH by 2-oxoglutarate dehydrogenase, and report the inactivation of the dehydrogenase in mitochondria by simultaneous addition of 2-oxoglutarate and t-BuOOH. Using the purified enzyme, we confirmed that t-BuOOH-induced inactivation of 2-oxoglutarate dehydrogenase was enhanced by its substrate and thiamine pyrophosphate protected the dehydrogenase from the inactivation. In contrast, succinate-dependent oxidation of mitochondria was not only scarcely affected by t-BuOOH, but also succinate protected against inactivation of 2-oxoglutarate dehydrogenase by t-BuOOH in mitochondria.
mesh_terms: D000818:Animals; D005260:Female; D005978:Glutathione / Q000378:metabolism; D007655:Ketoglutarate Dehydrogenase Complex / Q000037:antagonists & inhibitors*; D007656:Ketoglutaric Acids / Q000494:pharmacology*; D007658:Ketone Oxidoreductases / Q000037:antagonists & inhibitors*; D008054:Lipid Peroxides / Q000096:biosynthesis; D008930:Mitochondria, Liver / Q000201:enzymology*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D010545:Peroxides / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D020122:tert-Butylhydroperoxide
chemical_list: D007656:Ketoglutaric Acids; D008054:Lipid Peroxides; D010545:Peroxides; D009243:NAD; D009249:NADP; D020122:tert-Butylhydroperoxide; D007658:Ketone Oxidoreductases; D007655:Ketoglutarate Dehydrogenase Complex; D005978:Glutathione