The Separation and Partial Purification of the Soluble 17α- and 17β-Hydroxysteroid Dehydrogenases of Rabbit Liver

Abstract

17-Hydroxysteroid dehydrogenase activity toward 17α-estradiol, 17β-estradiol, and the 3-glucuronide derivatives of these steroids has been demonstrated in the 105 000 × g supernatant of rabbit liver. DEAE-cellulose chromatography of the enzyme activities isolated by calcium phosphate gel fractionation and Sephadex gel filtration yielded a single 17α-hydroxysteroid dehydrogenase activity toward both 17α-estradiol and 17α-estradiol 3-glucuronide. However, separate 17β-hydroxysteroid dehydrogenase activities toward 17β-estradiol and 17β-estradiol 3-glucuronide were obtained. Further purification of the 17α-hydroxysteroid dehydrogenase fraction by isoelectric focusing resulted in multiple peaks of activity toward 17α-estradiol and 17α-estradiol 3-glucuronide. One of these enzyme activities was highly specific for the 3-glucuronide derivative, it being essentially devoid of activity toward 17α-estradiol.