17α and 17β-oxidoreductases of adult female hamster liver and kidney

Abstract

The liver and kidney cytosols of adult female hamsters converted androstenedione to epitestosterone and testosterone and small quantities of 5β-androstanes. The kidney and liver cytosols were more effective in the production of epitestosterone with NADH than NADPH as coenzyme. The coenzymes had a reverse effect in the production of testosterone. Maximum production of epitestosterone occurred at pH 6.0 then gradually decreased with increase to pH 7.5. Testosterone production did not show a decrease until about pH 7.5. Liver homogenate stimulated the production of primarily highly polar metabolites. NADPH was more effective than NADH. This activity was localized in the microsomal fraction. Liver homogenate and microsomes also produced testosterone, epitestosterone and androstane-3α, 17β-diol. NADH was more effective than NADPH in the production of testosterone and epitestosterone but the reverse occurred in the production of 5β-androstane-3α,17β-diol. NADPH also effected the production of a small quantity of 3α-hydroxy-5β-androstan-17-one by both the homogenate and microsomes. The cytosol of the kidney converted testosterone only to traces of 5β-androstanes while the liver cytosol yielded appreciable quantities of 5β-androstane-3α,17β-diol and smaller quantities of the 3β-diol; NADPH was more effective than NADH. The NADPH system also produced androstenedione. Both the liver and kidney also exhibited strong 17β-hydroxy dehydrogenase activity. The activity in the cytosol of both tissues was stronger with NAD + than NADP + while it was much stronger with NAD + in the liver microsomes and with NADP + in the kidney microsomes. Spectrophotometric assay of the liver cytosol with NADP + revealed not only 17β-hydroxy dehydrogenase activity but also almost equal 17α-hydroxy and very high 3α-hydroxy dehydrogenase activity. The pH optimum for the 17β- and 17α-hydroxy activities was essentially the same, about 9.8, while that for the 3α-hydroxy activity was slightly higher, 10.5.