摘要：Hepatic estradiol-17β dehydrogenase from chickens catalyzed the reduction of the 3-keto group of androgens such as 5α-dihydrotestosterone and 5α-androstane-3, 17-dione as well as the 17-ketoreduction of 4-androstene-3, 17-dione and dehydroepiandrosterone. The reaction products from 17-ketosteroid and 3-ketosteroid substrates were identified as 17β-hydroxysteroids and 3β-hydroxysteroids, respectively, by thin layer chromatography, high performance liquid chromatography and gas chromatography. Barbital inhibited both 17β-estradiol dehydrogenase and 5α-androstane-3, 17-dione reductase activity noncompetitively giving the same kinetic constant, Ki=50 μM. 5α-Androstane-3, 17-dione competitively inhibited 17β-estradiol dehydrogenase activity. These results indicate that chicken liver estradiol-17β dehydrogenase is in fact a 3β-and 17β-hydroxysteroid dehydrogenase and that both 3- and 17-ketosteroids bind to the same catalytic site.
