Ichihara K, Tanaka C
Department of Biochemistry, Kawasaki Medical School, Okayama, Japan.
J Steroid Biochem. 1989 Jun;32(6):835-40. doi: 10.1016/0022-4731(89)90460-3.
The microsomes from guinea pig gastric mucosa were found to convert [4-14C]progesterone to two major metabolites in the presence of NADPH. The gastric metabolizing activity was the highest among the gastrointestinal tissues of guinea pig. 5 alpha-Pregnane-3,20-dione and 3 beta-hydroxy-5 alpha-pregnan-20-one were identified as the major metabolites by thin-layer chromatography and crystallization to constant specific activity, suggesting the presence of steroid 5 alpha-reductase and 3 beta-hydroxysteroid dehydrogenase activities in the gastric mucosa microsomes. Furthermore, time course of progesterone metabolism and analysis of 5 alpha-pregnane-3,20-dione metabolites suggest that the gastric progesterone metabolism is initiated by 5 alpha-reductase and followed by 3 beta-hydroxysteroid dehydrogenase. The progesterone-metabolizing activity was strongly inhibited by SKF 525-A and disulfiram. The activity was also inhibited by methyrapone to a somewhat lesser extent than the above inhibitors. From gastric mucosa microsomes, the progesterone-metabolizing activity was successfully solubilized with 2% digitonin using 0.1 M potassium chloride and 1 mM dithiothreitol, 0.4 mM NADPH and 20% glycerol as stabilizers for the solubilized activity. Among these stabilizers, glycerol was found to be most effective for stabilizing the activity of the solubilized microsomes.
发现在存在烟酰胺腺嘌呤二核苷酸磷酸（NADPH）的情况下，豚鼠胃黏膜微粒体能将[4-¹⁴C]孕酮转化为两种主要代谢产物。豚鼠胃的代谢活性在其胃肠道组织中是最高的。通过薄层层析和结晶至恒定比活性，鉴定出5α-孕烷-3,20-二酮和3β-羟基-5α-孕烷-20-酮为主要代谢产物，这表明胃黏膜微粒体中存在类固醇5α-还原酶和3β-羟基类固醇脱氢酶活性。此外，孕酮代谢的时间进程以及对5α-孕烷-3,20-二酮代谢产物的分析表明，胃中的孕酮代谢由5α-还原酶启动，随后是3β-羟基类固醇脱氢酶。孕酮代谢活性受到SKF 525-A和双硫仑的强烈抑制。该活性也受到甲吡酮的抑制，但其抑制程度比上述抑制剂略小。从胃黏膜微粒体中，使用0.1 M氯化钾和1 mM二硫苏糖醇、0.4 mM NADPH以及20%甘油作为溶解活性的稳定剂，用2%洋地黄皂苷成功溶解了孕酮代谢活性。在这些稳定剂中，发现甘油对稳定溶解的微粒体活性最为有效。
