Bhavnani B R, Woolever C A
Endocrinology. 1978 Dec;103(6):2291-8. doi: 10.1210/endo-103-6-2291.
A mixture of [4,8,12-14C]farnesyl pyrophosphate and [3H]dehydroepiandrosterone was injected into a horse fetus im during laparotomy, after which maternal urine was collected for 6 days. Steroid conjugates in the urine were extracted with Amberlite XAD-2 resin, hydrolyzed, and separated into phenolic and neutral fractions. Estrone, 17 alpha-estradiol, equilin [3-hydroxy-1,3,5(10),7-estratetraen-17-one], and 17 alpha-dihydroequilin [1,3,4(10),7-estratetraene-3,17 alpha-diol] were isolated from the phenolic fraction and their radiochemical purities were established. Only estrone and 17 alpha-estradiol contained both 3H and 14C, while the B ring unsaturated estrogens, equilin and 17 alpha-dihydroequilin, contained only 14C. From the neutral fraction, 14C-labeled 3 beta-hydroxy-5 alpha-pregnan-20-one, 5 alpha-pregnane-3 beta-20 beta-diol, and 5 alpha-pregnane-3 beta, 20 alpha-diol were isolated. These results together with our previous findings demonstrate that the route of biosynthesis of both the ring B saturated and unsaturated estrogens is the same up to the stage of farnesyl pyrophosphate. Thus, the bifurcation in the classical pathway of steroid biosynthesis is occurring at a point after the formation of farnesyl pyrophosphate and before the formation of squalene and cholesterol.
将[4,8,12 - 14C]法呢基焦磷酸酯和[3H]脱氢表雄酮的混合物在剖腹术期间注入马胎儿体内，之后收集母马尿液6天。尿液中的类固醇结合物用Amberlite XAD - 2树脂提取、水解，然后分离为酚类和中性馏分。从酚类馏分中分离出雌酮、17α - 雌二醇、马萘雌酮[3 - 羟基 - 1,3,5(10),7 - 雌甾四烯 - 17 - 酮]和17α - 二氢马萘雌酮[1,3,4(10),7 - 雌甾四烯 - 3,17α - 二醇]，并确定了它们的放射化学纯度。只有雌酮和17α - 雌二醇同时含有3H和14C，而B环不饱和雌激素马萘雌酮和17α - 二氢马萘雌酮仅含有14C。从中性馏分中分离出14C标记的3β - 羟基 - 5α - 孕烷 - 20 - 酮、5α - 孕烷 - 3β,20β - 二醇和5α - 孕烷 - 3β,20α - 二醇。这些结果与我们之前的发现共同表明，直到法呢基焦磷酸酯阶段，B环饱和和不饱和雌激素的生物合成途径是相同的。因此，类固醇生物合成经典途径中的分支发生在法呢基焦磷酸酯形成之后、角鲨烯和胆固醇形成之前的某个点。
