JBC, Vol. 253, Issue 12, 4237-4241, Jun, 1978
Formation of 5-[17beta-2H]androstene-3beta,17alpha-diol from 3beta-hydroxy-5-[17,21,21,21-2H]pregnen-20-one by the microsomal fraction of boar testis
K. Shimizu
After incubation of 3beta-hydroxy-5-[17,21,21,21-2H]-pregnen-20-one with
the microsomal fraction of boar testis, the metabolites were analyzed by
gas chromatography and gas chromatography-mass spectrometry. The following
metabolites were identified:
3beta,17alpha-dihydroxy-5-[21,21,21-3H]pregnen-20-one,
3beta-hydroxy-5-androsten-17-one, 5-androstene-3beta,17beta-diol, and
5-[17beta-2H]androstene-3beta,17alpha-diol. The presence of a 2H atom at
the 17beta position of 5-androstene-3beta,17alpha-diol was confirmed by
oxidizing the steroid with 3beta-hydroxy-steroid dehydrogenase of
Pseudomonas testosteroni to obtain 17alpha-hydroxy-4-[2H]androsten-3-one
and then by oxidizing the latter steroid with chromic acid to obtain
nonlabeled 4-androstene-3,17-dione. Among these metabolites, the first
three can be interpreted to be synthesized by a well documented pathway,
including 17alpha-hydroxylation followed by side chain cleavage as follows:
3beta-hydroxy-5-[17,21,21,21-2H]pregnen-20-one leads to
3beta,17alpha-dihydroxy-2-[21,21,212H]-pregnen-20-one leads to
3beta-hydroxy-5-androsten-17-one leads to 5-androstene-3beta,17beta-diol.
On the other hand, 5-androstene-3beta,17alpha-diol, which contained a 2H
atom at the 17beta position, is not likely to be synthesized via above
mentioned pathway in which nonlabeled 3beta-hydroxy-5-androsten-17-one is
formed as the first C19-steroid. It seems that an alternate side chain
cleavage mechanism leading from pregnenolone to 17alpha-hydroxy-C19-steroid
exists in boar testis.
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