Rokutan K, Kawai K, Asada K
J Biochem. 1987 Feb;101(2):415-22. doi: 10.1093/oxfordjournals.jbchem.a121926.
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.
大鼠肝脏线粒体中的酮酸氧化对叔丁基过氧化氢（t-BuOOH）非常敏感。此外，2-氧代戊二酸和丙酮酸各自增强了t-BuOOH诱导的线粒体氧化应激，如吡啶核苷酸和谷胱甘肽的氧化、对其他NAD连接底物呼吸作用的抑制以及线粒体脂质的过氧化。我们提供证据表明，t-BuOOH和酮酸诱导的效应是由于2-氧代戊二酸脱氢酶供应NADH失败所致，并报告了同时添加2-氧代戊二酸和t-BuOOH时线粒体中该脱氢酶的失活。使用纯化的酶，我们证实t-BuOOH诱导的2-氧代戊二酸脱氢酶失活被其底物增强，硫胺素焦磷酸保护该脱氢酶免于失活。相反，线粒体的琥珀酸依赖性氧化不仅几乎不受t-BuOOH影响，而且琥珀酸还能保护线粒体中的2-氧代戊二酸脱氢酶免于t-BuOOH诱导的失活。
