Abstract:
:5 alpha-Dihydrotestosterone, the principal androgen mediating prostate growth and function in the rat, is formed from testosterone by steroid 5 alpha-reductase. The inactivation of 5 alpha-dihydrotestosterone involves reversible reduction to 5 alpha-androstane-3 beta,17 beta-diol by 3 beta-hydroxysteroid oxidoreductase followed by 6 alpha-, 7 alpha-, or 7 beta-hydroxylation. 5 alpha-Androstane-3 beta,17 beta-diol hydroxylation represents the ultimate inactivation step of dihydrotestosterone in rat prostate and is apparently catalyzed by a single, high-affinity (Km approximately 0.5 microM) microsomal cytochrome P450 enzyme. The present studies were designed to determine if 5 alpha-androstane-3 beta,17 beta-diol hydroxylation by rat prostate microsomes is inhibited by agents that are known inhibitors of androgen-metabolizing enzymes. Inhibitors of steroid 5 alpha-reductase (4-azasteroid analogs; 10 microM) or inhibitors of 3 beta-hydroxysteroid oxidoreductase (trilostane, azastene, and cyanoketone; 10 microM) had no appreciable effect on the 6 alpha-, 7 alpha-, or 7 beta-hydroxylation of 5 alpha-androstane-3 beta,17 beta-diol (10 microM) by rat prostate microsomes. Imidazole-type antimycotic drugs (ketoconazole, clotrimazole, and miconazole; 0.1-10 microM) all markedly inhibited 5 alpha-androstane-3 beta,17 beta-diol hydroxylation in a concentration-dependent manner, whereas triazole-type antimycotic drugs (fluconazole and itraconazole; 0.1-10 microM) had no inhibitory effect. The rank order of inhibitory potency of the imidazole-type antimycotic drugs was miconazole greater than clotrimazole greater than ketoconazole. In the case of clotrimazole, the inhibition was shown to be competitive in nature, with a Ki of 0.03 microM. The imidazole-type antimycotic drugs inhibited all three pathways of 5 alpha-androstane-3 beta,17 beta-diol hydroxylation to the same extent, which provides further evidence that, in rat prostate microsomes, a single cytochrome P450 enzyme catalyzes the 6 alpha-, 7 alpha-, and 7 beta-hydroxylation of 5 alpha-androstane-3 beta,17 beta-diol. These studies demonstrate that certain imidazole-type compounds are potent, competitive inhibitors of 5 alpha-androstane-3 beta,17 beta-diol hydroxylation by rat prostate microsomes, which is consistent with the effect of these antimycotic drugs on cytochrome P450 enzymes involved in the metabolism of other androgens and steroids.
journal_name
Arch Biochem Biophysjournal_title
Archives of biochemistry and biophysicsauthors
Gemzik B,Parkinson Adoi
10.1016/0003-9861(92)90586-lsubject
Has Abstractpub_date
1992-08-01 00:00:00pages
366-73issue
2eissn
0003-9861issn
1096-0384pii
0003-9861(92)90586-Ljournal_volume
296pub_type
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journal_title:Archives of biochemistry and biophysics
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
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更新日期:1983-08-01 00:00:00
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pub_type: 杂志文章
doi:10.1016/j.abb.2017.11.001
更新日期:2017-12-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2005.10.025
更新日期:2006-02-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2019.03.005
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(91)90591-6
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章,评审
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2007.04.017
更新日期:2007-08-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.1995.1132
更新日期:1995-02-20 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(88)90569-3
更新日期:1988-07-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2009.07.018
更新日期:2009-09-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章,评审
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更新日期:2003-12-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2006.09.003
更新日期:2006-11-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.2001.2283
更新日期:2001-04-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2011.11.024
更新日期:2012-02-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(91)90355-m
更新日期:1991-03-01 00:00:00
abstract::XynA from Erwinia chrysanthemi (EcXyn30A), belonging to glycoside hydrolase family 30 subfamily 8, is specialized for hydrolysis of 4-O-methylglucuronoxylan (GX). Carboxyl group of 4-O-methylglucuronic acid serves as a substrate recognition element interacting ionically with positively charged Arg293 of the enzyme. We...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2018.02.014
更新日期:2018-04-02 00:00:00