Abstract
Summary DEAE cellulose chromatography achieved the separation of several 17 β hydroxysteroid NAD (P) oxidoreductase activities from rabbit liver cytosol; two of these activities differ strongly by their anionic character and electrophoretic mobility, as well as by their substrate or coenzyme specificity; the purification of these two fractions (A and C) was performed further. The fraction A contains a weakly anionic 17 β hydroxysteroid oxidoreductase. Its molecular weight is about 25 – 30 000 (sephadex G 100 filtration), both testosterone and estradiol are substrates; NAD or NADP are coenzymes, and the Km for testosterone is 5.10−4 M. From the second fraction (C) was separated a very anionic testosterone NADP oxidoreductase with high affinity for testosterone (Km 3 ± 0,5 10−6 M). The four isozymes shown by polyacrylamide gel electrophoresis are resolved into a single peptid chain of M.W. 36 000 by SDS polyacrylamide gel electrophoresis. The purified enzyme of fraction (C) exhibits a high 3α hydroxysteroid NADP oxidoreductase activity: experimental results are given showing electrophoretic and kinetic evidences for the identity of these two enzymes in fraction C of the adult female rabbit.
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