Johnson D C, Griswold T
J Steroid Biochem. 1984 Mar;20(3):733-9. doi: 10.1016/0022-4731(84)90077-3.
The steroid C17,20-lyase activity of immature rat ovarian microsomal (105,000 g pellet), mitochondrial (10,000 g pellet) and combined fractions was measured using progesterone and 17-hydroxyprogesterone as substrates. Steroid 17 alpha-hydroxylase was measured, using progesterone as substrate, in some of the preparations for comparison. With progesterone about 3.5 times more product (acetic acid) was formed than with 17-hydroxyprogesterone as substrate. The half-time for lyase activity following hypophysectomy was 51.8 h, while that for 17 alpha-hydroxylase was 51.3 h. Following an intravenous injection of 20 iu of pregnant mare's serum gonadotropin (PMS) into immature hypophysectomized rats lyase activity decreased for 12 h followed by recovery during the next 12 h with a rapid increase between 24 and 72 h. In contrast, a subcutaneous injection of the same dose produced an initial rise in activity with a decline between 12 and 24 h, followed by a second large increase. In intact animals injection (s.c.) of PMS produced an initial fall in lyase activity followed by an increase beginning 12 h later. A dramatic decrease in activity occurred between 48 and 72 h concomitant with ovulation; hypophysectomy at 48 h not only prevented the decrease, but produced an increase in activity. The changes in ovarian C17,20-lyase activity following administration of PMS mimic those of 17 alpha-hydroxylase.
以孕酮和17-羟孕酮为底物，测定未成熟大鼠卵巢微粒体（105,000g沉淀）、线粒体（10,000g沉淀）及混合组分的类固醇C17,20-裂解酶活性。在部分制剂中以孕酮为底物测定类固醇17α-羟化酶活性，以便进行比较。以孕酮为底物时生成的产物（乙酸）比以17-羟孕酮为底物时多约3.5倍。垂体切除术后裂解酶活性的半衰期为51.8小时，而17α-羟化酶的半衰期为51.3小时。给未成熟垂体切除的大鼠静脉注射20国际单位的孕马血清促性腺激素（PMS）后，裂解酶活性在12小时内下降，随后在接下来的12小时内恢复，并在24至72小时之间迅速增加。相比之下，皮下注射相同剂量则使活性最初升高，在12至24小时之间下降，随后再次大幅增加。在完整动物中，皮下注射PMS使裂解酶活性最初下降，随后在12小时后开始升高。在48至72小时之间，伴随着排卵，活性急剧下降；在48小时进行垂体切除不仅阻止了活性下降，反而使活性增加。给予PMS后卵巢C17,20-裂解酶活性的变化与17α-羟化酶的变化相似。
