Metabolism of 32-hydroxylated 24,25-dihydrolanosterols by partially purified cytochrome P-45014DM from rat liver microsomes.
作者:YOSHIO SEKIGAWA、YOSHIKO SONODA、YOSHIHIRO SATO
DOI:10.1248/cpb.36.3049
日期:——
Metabolism of 32-hydroxylated 24, 25-dihydrolanosterols (1-3), including the intermediate of lanosterol and 24, 25-dihydrolanosterol (4, DHL) demethylation, were studied in a reconstituted system consisting of rat liver partially purified cytochrome P-450, which catalyzes lanosterol 14-demethylation (cytochrome P-45014DM), and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P-450 reductase. The reconstituted system converted lanost-8-ene-3β, 32-diol (1) to 4, 4-dimethyl-5α-cholesta-8, 14, dien-3β-ol (5), the 14-dehydroxymethylated product, in the same way as 4. Lanost-7-ene-3β-32-diol (2) and lanost-6-ene-3β, 32-diol (3), the isomers of 1, were not converted to the corresponding 14-dehydroxymethylated products. The apparent Km value of cytochrome P-45014DM for 1 was about 1/6 of that for 4. The metabolism of 4 was inhibited by 7-oxo-24, 25-dihydrolanosterol (6, 7-oxo-DHL), which is a potent inhibitor of cholesterol biosynthesis from lanosterol or 4. However, the metabolism of 1 was less inhibited by 6 than that of 4.
在由大鼠肝脏部分纯化的细胞色素 P-450 组成的重组系统中,研究了 32- 羟基化的 24,25-二氢羊毛甾醇(1-3)的代谢,包括羊毛甾醇和 24,25-二氢羊毛甾醇(4,DHL)去甲基化的中间产物、和还原型烟酰胺腺嘌呤二核苷酸磷酸酯(NADPH)-细胞色素 P-450 还原酶组成的重组系统中进行了研究。重组系统将羊毛甾-8-烯-3β,32-二醇(1)转化为 4,4-二甲基-5α-胆甾烷-8,14,二烯-3β-醇(5),即 14-脱羟甲基化产物,转化方式与 4 相同。1 的细胞色素 P-45014DM 表观 Km 值约为 4 的 1/6。7-oxo-24, 25-dihydrolanosterol (6,7-oxo-DHL) 可抑制 4 的新陈代谢,后者是由羊毛甾醇或 4 合成胆固醇的有效抑制剂。不过,与 4 相比,6 对 1 的代谢抑制作用较弱。