文章基本信息

标题：Cholic acid biosynthesis: conversion of 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol into 5beta-cholestane-3alpha,7alpha, 12alpha,24beta,25-pentol by human and rat liver microsomes.
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作者：F W Cheng ; S Shefer ; B Dayal 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：1977
卷号：18
期号：1
页码：6-13
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：This paper describes the conversion of 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol into 5beta-cholestane-3alpha,7alpha,12alpha,24beta,25-pentol by liver microsomes. A sensitive radioactive assay for measuring the formation of 5beta-cholestane-3alpha,7alpha,12alpha,24beta,25-pentol was developed. Optimal assay conditions for human and rat microsomal systems were established. A higher 24beta-hydroxylation activity was detected in rat than in human liver under the conditions employed. The hydroxylation of 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol by the rat liver microsomal fraction fortified with NADPH was stimulated about two-fold by administration of phenobarbital. Phenobarbital treatment also stimulated hydroxylations at C-23, C-24alpha, and C-26. Carbon monoxide markedly inhibited all side-chain hydroxylations. In contrast, side-chain hydroxylase activities were not affected in animals deprived of food for 48 hr. These results are consistent with a previously postulated cholic acid biosynthetic pathway involving 5beta-cholestane-3alpha,7alpha,12alpha,24beta,25-pentol as a key intermediate in man and in the rat.