Kühn-Velten N, Staib W
J Steroid Biochem. 1984 Dec;21(6):697-700. doi: 10.1016/0022-4731(84)90033-5.
Use of integrated rate equations for analysis of progesterone metabolism by isolated Leydig cells and microsomes from rat testis in presence of several progesterone concentrations within several periods reveals competitive product inhibition by endogenously formed 17 alpha-hydroxyprogesterone (Kpm = 0.1 microM) of steroid-17 alpha-monooxygenase activity (Ksm = 0.8 microM). The discrepancy between this very low interaction constant of endogenous 17 alpha-hydroxyprogesterone with the steroid-17 alpha-monooxygenase, and the respective values (from the literature) for exogenous 17 alpha-hydroxyprogesterone which are about 50-fold higher, may be explained by accumulation of endogenous 17 alpha-hydroxyprogesterone at the catalytic site of the steroid-17 alpha-monooxygenase. This mechanism may be important for intratesticular regulation of androgen biosynthesis from precursor steroids.
在几个时间段内，在几种孕酮浓度存在的情况下，使用积分速率方程分析来自大鼠睾丸的分离的睾丸间质细胞和微粒体中的孕酮代谢，结果显示内源性生成的17α-羟基孕酮（Kpm = 0.1微摩尔）对类固醇-17α-单加氧酶活性（Ksm = 0.8微摩尔）具有竞争性产物抑制作用。内源性17α-羟基孕酮与类固醇-17α-单加氧酶的这种非常低的相互作用常数，与外源性17α-羟基孕酮（来自文献）的相应值相比约高50倍，这一差异可能是由于内源性17α-羟基孕酮在类固醇-17α-单加氧酶的催化位点积累所致。这种机制对于睾丸内从前体类固醇生物合成雄激素的调节可能很重要。
