Sanai Y, Suzuki T, Yanaihara T, Nakayama T
Nihon Sanka Fujinka Gakkai Zasshi. 1984 Feb;36(2):195-201.
To study the biosynthesis of 20 alpha-dihydropregnenolone-sulfate (20P5-S) and 20 alpha-dihydroprogesterone (20P4) in the feto-placental unit, human fetal liver and placenta were incubated with various radioactive precursors which included 14C-pregnenolone (P5), 14C-progesterone (P4), 14C-20 alpha-dihydropregnenolone (20P5) and 14C-20P5-S. In fetal liver, it was found that sulfokinase and 20 alpha-hydroxysteroid dehydrogenase (20HSD) activities were localized in 105,000xg supernatant obtained by a conventional differential centrifugation method. As cofactors, sulfokinase and 20HSD require ATP and NADPH, respectively. When P5 was incubated for varying periods with 105,000xg supernatant of liver homogenate, the precursor decreased with incubation time, whereas labeled 20P5-S increased steadily. A rapid increase in the 20P5 followed by declining amounts with further incubation occurred, suggesting a possible role of 20P5 as intermediates in 20P5-S formation from P5. When 20P-S was used as a precursor in the incubation with placental homogenate for different periods of time, rapid conversion to P4 was observed with a bell-shaped curve depicting 20P5 and 20P4 whereas the recovery of P5 remained low throughout the incubation period. These in vitro results indicate that the placental P4 and 20P4 might be synthesized, in part, from 20P5-S which is derived from fetal liver during pregnancy.
为研究胎儿 - 胎盘单位中20α - 二氢孕烯醇酮硫酸盐（20P5 - S）和20α - 二氢孕酮（20P4）的生物合成，将人胎儿肝脏和胎盘与多种放射性前体一起孵育，这些前体包括14C - 孕烯醇酮（P5）、14C - 孕酮（P4）、14C - 20α - 二氢孕烯醇酮（20P5）和14C - 20P5 - S。在胎儿肝脏中，发现磺激酶和20α - 羟基类固醇脱氢酶（20HSD）活性定位于通过传统差速离心法获得的105,000xg上清液中。作为辅助因子，磺激酶和20HSD分别需要ATP和NADPH。当P5与肝脏匀浆的105,000xg上清液孵育不同时间时，前体随孵育时间减少，而标记的20P5 - S稳步增加。20P5先快速增加，随后随着进一步孵育量下降，这表明20P5可能作为从P5形成20P5 - S的中间体。当20P - S用作与胎盘匀浆孵育不同时间段的前体时，观察到其快速转化为P4，呈现出描绘20P5和20P4的钟形曲线，而在整个孵育期间P5的回收率仍然很低。这些体外实验结果表明，胎盘P4和20P4可能部分由孕期胎儿肝脏来源的20P5 - S合成。
