PMID: 37613Jun 1, 1979

Characterization of two new enzymatic activities of the rat ventral prostate: 5 alpha-androstane-3 beta, 17 beta-diol 6 alpha-hydroxylase and 5 alpha-androstane-3 beta, 17 beta-diol 7 alpha-hydroxylase

Steroids
J T IsaacsD S Coffey

Abstract

This study has characterized two new enzymatic hydroxylase activities specific for 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) in the rat ventral prostate: 5 alpha-androstane-3 beta, 17 beta-diol 6 alpha-hydroxylase (6 alpha-hydroxylase) and 5 alpha-androstane-3 beta, 17 beta-diol 7 alpha-hydroxylase (7 alpha-hydroxylase). Both of these irreversible hydroxylase activities require NADPH and are localized in the microsomal fraction of the prostate. The apparent Km for 3 beta-diol is 2.5 microM for both the 6 alpha- and 7 alpha-hydroxylase activities. The apparent Km for NADPH is 7.6 microM for the 6 alpha-hydroxylase and 7.0 microM for the 7 alpha-hydroxylase. The pH optimum for both activities is 7.4. Several steroid inhibitors of these hydroxylase activities in vitro were identified including cholesterol, progesterone, and estradiol. Estradiol was found in vitro to be a noncompetitive inhibitor (Ki = 5 microM). Injection of estradiol into intact male rats, simultaneously receiving exogenous testosterone, also produced a significant lowering of the 6 alpha-plus 7 alpha-hydroxylase activities. Both the 6 alpha- and 7 alpha-hydroxylase were found to be androgen sensitive. Following castration there is a rapid decrease in...Continue Reading

References

Jun 28, 2003·FEBS Letters·Zhang WeihuaJan-Ake Gustafsson
May 9, 2009·International Journal of Urology : Official Journal of the Japanese Urological Association·Takayuki KurosakiTadaichi Kitamura
Feb 16, 2005·Proceedings of the National Academy of Sciences of the United States of America·Yoko OmotoJan-Ake Gustafsson

Related Concepts

Testosterone Measurement
Epicholesterol
Microsomes
7alpha hydroxylase
Estradiol Measurement
Progesterone
Androgens
Progesterone [EPC]
Progesterone Measurement
androstane, (5alpha)-isomer

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