title: Canine testicular 17beta-hydroxysteroid oxidoreductase activity. I. Substrate specificity.
abstract: The substrate specificity of 17beta-hydroxysteroid oxidoreductase (17beta-HOR) activity was investigated in microsomal preparations of canine testes. Enzyme activity was measured by quantitating the conversion of radioactive substrates to products. The apparent Michaelis constants were determined to be 1.3 x 10(-6)M for androstenendione, 3--10 x 10(-6)M for dehydroepiandrosterone and 25 x 10(-6)M for estrone. These data are similar to those reported for human testicular 17beta-HOR activity and suggest that the canine activity may serve as an animal model for the study of testicular 17beta-HOR.
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000735:Androstenedione; D000818:Animals; D003687:Dehydroepiandrosterone; D004285:Dogs; D004970:Estrone; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D013379:Substrate Specificity; D013737:Testis / Q000201:enzymology*
chemical_list: D004970:Estrone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D015067:17-Hydroxysteroid Dehydrogenases