Premium
2‐Hydroxylation of pregnenolone by rat liver microsomes
Author(s) -
Danielsson Henry,
Johansson Gunnar
Publication year - 1972
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(72)80516-7
Subject(s) - chemistry , hydroxylation , library science , philosophy , biochemistry , computer science , enzyme
The microsomal fraction of liver homogenate catalyzes hydroxylation of steroids in a number of different positions [ 11. The positions hydroxylated often vary with the steroid and a given steroid is frequently hydroxylated only in a limited number of positions. Different steroids may be hydroxylated in the same position or positions. The question of the multiplicity of the enzyme system catalyzing hydroxylation of steroids has not been resolved nor are the factors governing the positional specificity of the enzyme system(s) known. In a recent report from this laboratory some aspects of the microsomal hydroxyiation of cholesterol, pregnenolone* and dehydroepiandrosterone were studied with the aim of gathering information relevant to these questions [2]. Part of the investigation concerned the properties of the system(s) catalyzing 7a-hydroxylation of these substrates. Marked differences were observed between 7ar-hydroxylation of cholesterol and 7~ hydroxylation of pregnenolone and dehydroepiandrosterone. The pattern of hydroxylations of pregnenolone and dehydroepiandrosterone also differed. Whereas the 7a-hydroxylated derivative was a major product of dehydroepiandrosterone, 7at-hydroxyprenenolone was a minor product of prenenolone. Instead, an unidentified compound or compounds with thin-layer chromatographic properties similar to those of 7/3-hydroxypregnenolone was the major product. The present communication reports the identification of the unknown as a mixture of about 85% 2&-hydroxypregnenolone and about 15% of 2& hydroxypregnenolone.