20BETA-HYDROXYSTEROID - NAD OXIDOREDUCTASE ACTIVITY TOWARDS 3BETA-HYDROXYPREGN-5-EN-20-ONE SULPHATE AND RELATED FREE STEROIDS

被引：5

作者：

POCKLING.T

JEFFERY, J

机构：

[1] University of Aberdeen, Department of Obstetrics, Gynaecology Clinical Research Unit, The Matcmity Hospital, Aberdeen

[2] University of Aberdeen, Department of Chemical Pathology, Aberdeen, AB9 2ZD, Medical School Buildings

来源：

EUROPEAN JOURNAL OF BIOCHEMISTRY | 1969年 / 9卷 / 01期

关键词：

D O I：

10.1111/j.1432-1033.1969.tb00587.x

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The sulphate of 3β‐hydroxypregn‐5‐en‐20‐one is now reported to be a substrate for crystalline 20β‐hydroxysteroid: NAD oxidoreductase prepared from Streptomyces hydrogenans. Utilization of this steroid sulphate was not independent of activity towards pregn‐4‐ene‐3,20‐dione or 3β‐acetoxypregn‐5‐en‐20‐one, but the total rate of reaction for equimolar mixtures of 3β‐hy‐droxypregn‐5‐en‐20‐one sulphate and either pregn‐4‐ene‐3,20‐dione or 3β‐acetoxypregn‐5‐en‐20‐one was less than that calculated for the simplest type of mutual competitive inhibition, particularly at low substrate concentrations. The Michaelis constant for NADH was similar (about 5 μM) with each of these compounds as substrate. 3β‐Hydroxypregn‐5‐en‐20‐one, and its 17α‐hydroxy derivative behaved anomalously, and their behaviour is discussed. 3β,17α,21‐Trihydroxypregn‐5‐en‐20‐one was a good substrate and had kinetic constants similar to those of 17α,21‐dihydroxypregn‐4‐ene‐3,20‐dione. Copyright © 1969, Wiley Blackwell. All rights reserved

引用

页码：142 / &

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