title: 20 beta-hydroxysteroid dehydrogenase of neonatal pig testis: 3 alpha/beta-hydroxysteroid dehydrogenase activities catalyzed by highly purified enzyme.
abstract: Pig testicular 20 beta-hydroxysteroid dehydrogenase (20 beta-HSD) has also 3 alpha- and 3 beta-HSD (3 alpha/beta-HSD) activities. The purified 20 beta-HSD preparation from neonatal pig testes could catalyze the conversion of 5 alpha-dihydrotestosterone (5 alpha-DHT) in the presence of beta-NADPH to 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol at the ratio of 4:3, and the specific 3 alpha/beta-HSD activity of 20 beta-HSD for 5 alpha-DHT was about 10 or 15 times larger than the 20 beta-HSD activities for 17 alpha-hydroxypregn-4-ene-3,20-dione (17 alpha-hydroxyprogesterone) or progesterone, respectively. The result indicates that the testicular 20 beta-HSD has high 3 alpha(axial, 3R)- and 3 beta(equatorial, 3S)-HSD activity. The testicular 20 beta-HSD could catalyze the reversible conversion of various 5 alpha- or 5 beta-dihydrosteroids which have a 3-carbonyl or 3-hydroxyl group with beta-NADP(H) as the preferred cofactor. The enzyme transferred the 4-proS hydrogen of NADPH to the 5 alpha-DHT for both 3 alpha- and 3 beta-hydroxylation and it was the same as the 20 beta-hydroxylation of 17 alpha-hydroxyprogesterone. Although the 3 alpha/beta-HSD activity has been known to be present in 3 alpha,20 beta-HSD of Streptomyces hydrogenans, the enzymological properties for 3 alpha/beta-HSD activity catalyzed by testicular 20 beta-HSD were different from the properties for 3 alpha/beta-HSD activity catalyzed by prokaryotic 3 alpha, 20 beta-HSD with respect to the specificity of the catalytic reaction and the cofactor requirement.
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohno
authors.forename: S
authors.initials: S
authors.lastname: Nakajin
authors.forename: M
authors.initials: M
authors.lastname: Shinoda
mesh_terms: D019326:17-alpha-Hydroxyprogesterone; D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002384:Catalysis; D002413:Cations, Divalent; D003349:Cortisone Reductase / Q000302:isolation & purification / Q000378:metabolism*; D013196:Dihydrotestosterone / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D006908:Hydroxyprogesterones / Q000378:metabolism; D008297:Male; D009249:NADP / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D013379:Substrate Specificity; D013552:Swine; D013737:Testis / Q000201:enzymology*
chemical_list: D002413:Cations, Divalent; D006908:Hydroxyprogesterones; D013196:Dihydrotestosterone; D011374:Progesterone; D009249:NADP; D019326:17-alpha-Hydroxyprogesterone; D015096:3-Hydroxysteroid Dehydrogenases; D003349:Cortisone Reductase