Abstract
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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
