Evidence of conversion of estradiol 17-sulfate to its 2- and 4-hydroxylated catechols by human placental microsomes.
When estradiol 17-sulfate (ES) was incubated with human placental microsomes under an NADPH-generating system, 2- and 4-hydroxyestradiol 17-sulfates (2- and 4-OH-ES) formed as the main products. By kinetic experiments, the apparent Km values of 44.0 and 360 microM and apparent Vmax values of 236 and 140 pmol/mg protein/10 min were obtained for the 2- and 4-hydroxylation, respectively. The results indicate that human placental microsomes have fairly high 2- and 4-hydroxylase activities toward ES. This paper describes the formation of 2- and 4-OH-ES and speculates on their physiological role during pregnancy.
Takanashi
K
K
Hokkaido Institute of Pharmaceutical Sciences, Japan.
Watanabe
K
K
Yoshizawa
I
I
D001711:Biotransformation; D002396:Catechols / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004958:Estradiol / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D006900:Hydroxylation; D066298:In Vitro Techniques; D008861:Microsomes / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010920:Placenta / Q000378:metabolism* / Q000648:ultrastructure; D011247:Pregnancy
D002396:Catechols; C048615:estradiol 17-sulfate; D004958:Estradiol; D009249:NADP