Properties of NADH-dependent estradiol 2-hydroxylase in rat liver.
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.
D000818:Animals; D019363:Cytochrome P-450 CYP1A1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D009243:NAD; D009249:NADP; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D013250:Steroid Hydroxylases / Q000378:metabolism*
D009243:NAD; D009249:NADP; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D019363:Cytochrome P-450 CYP1A1; C020120:estrogen 2-hydroxylase