Inhibition study of human placental aromatase with 3-deoxy- and 6-oxo-steroids using [1 beta-3H]16 alpha-hydroxyandrostenedione as a substrate: a comparison to that using [1 beta-3H]androstenedione.
Inhibition of aromatase activity in human placental microsomes with 3-deoxy- (1, 2, 4, 6 and 8), 6-oxo- (3, 5 and 9), and 16 alpha-bromo- (7) steroids was studied using [1 beta-3H]16 alpha-hydroxyandrostenedione (16 alpha-OHAD) as a substrate and compared to that with the conventional substrate, [1 beta-3H]androstenedione. All the steroids inhibited both 16 alpha-OHAD and [1 beta-3H]androstenedione aromatization in a competitive manner. Based on Ki/Km ratios obtained in both series of experiments, their relative inhibitory activities in the series with 16 alpha-OHAD were not necessarily identical with those in the other series. The results would be important to understand the relationship of structure to function of aromatase in human placental microsomes.
Numazawa
M
M
Tohoku College of Pharmacy, Sendai, Japan.
Mutsumi
A
A
D000735:Androstenedione / Q000031:analogs & derivatives* / Q000378:metabolism*; D047072:Aromatase Inhibitors; D006801:Humans; D010920:Placenta / Q000201:enzymology*; D013256:Steroids / Q000737:chemistry / Q000494:pharmacology*; D013379:Substrate Specificity
D047072:Aromatase Inhibitors; D013256:Steroids; D000735:Androstenedione; C018202:16-hydroxyandrost-4-en-3,17-dione