The effects of adrenal and gonadal steroids and K+-canrenoate on the metabolism of aldosterone by rat liver microsomes
作者:Syed A. Latif、Martin J. McDermott、David J. Morris
DOI:10.1016/0039-128x(83)90040-5
日期:1983.9
The synthesis of polar aldosterone metabolites by rat liver microsomes at physiological concentrations of aldosterone (21.5 nM), was markedly inhibited by progesterone, testosterone, corticosterone, K+-canrenoate and estradiol-17 beta. In contrast, corticosterone and estradiol-17 beta significantly increased the synthesis of reduced aldosterone metabolites by 8- and 15-fold respectively, the majority of which were 5 alpha-reduced products of aldosterone. In experiments at higher substrate (aldosterone) concentrations (20-200 microM) the synthesis of ring A-reduced aldosterone metabolites by liver microsomes followed Michaelis-Menten kinetics with a Km[app] for aldosterone of 160 microM and Vmax[app] of 12.2 nmoles/mg protein/5 min. In these experiments progesterone, testosterone and K+-canrenoate all competitively inhibited the synthesis of reduced metabolites with inhibition constants (Ki [app]) of 70, 85 and 55 microM respectively; however, corticosterone did not. In contrast, estradiol-17 beta increased the rate of synthesis of reduced products by 40%, lowering the Km[app] to 83 microM.
Kirk, David N.; Rajagopalan, Maruthiandan S., Journal of the Chemical Society. Perkin transactions I, 1987, p. 1343 - 1346
作者:Kirk, David N.、Rajagopalan, Maruthiandan S.
DOI:——
日期:——
Substrate specificity and inhibitor analyses of human steroid 5β-reductase (AKR1D1)
作者:Mo Chen、Jason E. Drury、Trevor M. Penning
DOI:10.1016/j.steroids.2011.01.003
日期:2011.4
systematically determined the substrate specificity of homogeneous human recombinant AKR1D1 using C18, C19, C21, and C27 Δ(4)-ketosteroids and assessed the pH-rate dependence of the enzyme. Our results show that AKR1D1 proficiently reduced all the steroids tested at physiological pH, indicating AKR1D1 is the only enzyme necessary for all the 5β-steroid metabolites present in humans. Substrate inhibition was observed