Abstract
The female guinea pig kidney cytosol and microsomes contain a trace or no detectable NADP+ or NAD+-linked dehydrogenase activity for several hydroxy-C19-steroids. The administration of testosterone induced a gradual increase in the 17β-C19-steroid dehydrogenase activity of the cytosol, but not of the microsomes, to the level in the male after 50 days. The induced enzyme was purified by (NH4)2SO4 precipitation, Sephadex G-75 nitration and DEAE-Sephadex A-50 and CM-Sephadex C-50 chromatography to give a protein which gave a molecular weight of 32,000 and a single protein and enzyme staining band on gel electrophoresis. The pure enzyme dissociated into three gel electrophoretic bands on removal of 2-mercaptoethanol from the solution and was restored by replacement of the mercaptoethanol. The enzyme in the cytosol, however, dissociated on storage at 4°C for 48 h or longer in the presence or absence of 2-mercaptoethanol. The KM value, steroid specificity, gel electrophoretic pattern, isoelectric value, pH optimum and NADP+ and NAD+ requirement were practically identical with those of the purified major 17β-hydroxy-C19-steroid dehydrogenase of the male guinea pig kidney. The several hydroxy-C19-steroid dehydrogenase activities of the liver were not influenced by testosterone administration. The highest enzyme activity was exhibited with 5β-dihydrotestosterone as substrate.
Published Version
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