Mendoza-Hernández G, López-Solache I, Rendón J L, Díaz-Sánchez V, Díaz-Zagoya J C
Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, D. F., Mexico.
Biochem Biophys Res Commun. 1988 Apr 15;152(1):376-82. doi: 10.1016/s0006-291x(88)80724-1.
The mitochondrial fraction of the dog pancreas showed NAD(H)-dependent enzyme activity of 17 beta-hydroxysteroid dehydrogenase. The enzyme catalyzes oxidoreduction between androstenedione and testosterone. The apparent Km value of the enzyme for androstenedione was 9.5 +/- 0.9 microM, the apparent Vmax was determined as 0.4 nmol mg-1 min-1, and the optimal pH was 6.5. In phosphate buffer, pH 7.0, maximal rate of androstenedione reduction was observed at 37 degrees C. The oxidation of testosterone by the enzyme proceeded at the same rate as the reduction of the androstenedione at a pH of 6.8-7.0. The apparent Km value and the optimal pH of the enzyme for testosterone were 3.5 +/- 0.5 microM and 7.5, respectively.
犬胰腺的线粒体部分显示出17β-羟类固醇脱氢酶的NAD(H)依赖性酶活性。该酶催化雄烯二酮和睾酮之间的氧化还原反应。该酶对雄烯二酮的表观Km值为9.5±0.9微摩尔，表观Vmax确定为0.4纳摩尔毫克-1分钟-1，最佳pH值为6.5。在pH值为7.0的磷酸盐缓冲液中，在37℃观察到雄烯二酮还原的最大速率。在pH值为6.8-7.0时，该酶催化睾酮的氧化速率与雄烯二酮的还原速率相同。该酶对睾酮的表观Km值和最佳pH值分别为3.5±0.5微摩尔和7.5。
