Numazawa M, Soeda N, Kiyono Y, Nambara T
J Steroid Biochem. 1982 Aug;17(2):231-6. doi: 10.1016/0022-4731(82)90127-3.
The NADH-supported cytochrome P-450-dependent 2-hydroxylation of estradiol in rat liver microsomes has been investigated. Estradiol 2-hydroxylation proceeded well with NADH instead of NADPH as a cofactor. Dimethyltetrahydropterine was incapable of serving as a hydrogen donor for this biotransformation. When both NADH and NADPH were used, the 2-hydroxylation increased additively. Molecular oxygen dissolved in the incubation medium was enough for the occurrence of the NADH-dependent 2-hydroxylation. The presence of carbon monooxide suppressed the formation of catechol estrogen where the CO/O2 ratio needed for 50% inhibition of the bioconversion was 7.7. The inhibitory effect was reversed completely by illumination with white light. p-Chloromercuribenzoate inhibited almost completely the 2-hydroxylase activity, and the enzyme activity was also inhibited by SKF-525A. These results strongly imply the possible involvement of a cytochrome P-450 system in the NADH-dependent 2-hydroxylation of estradiol with rat liver microsomes.
对大鼠肝微粒体中NADH支持的细胞色素P-450依赖的雌二醇2-羟化反应进行了研究。以NADH而非NADPH作为辅因子时，雌二醇2-羟化反应进行良好。二甲基四氢蝶呤不能作为该生物转化的氢供体。当同时使用NADH和NADPH时，2-羟化反应呈累加性增加。溶解于孵育介质中的分子氧足以支持NADH依赖的2-羟化反应的发生。一氧化碳的存在抑制了儿茶酚雌激素的形成，50%抑制该生物转化所需的CO/O2比值为7.7。白光照射可完全逆转这种抑制作用。对氯汞苯甲酸几乎完全抑制2-羟化酶活性，SKF-525A也可抑制该酶活性。这些结果强烈表明，细胞色素P-450系统可能参与大鼠肝微粒体中NADH依赖的雌二醇2-羟化反应。
