Metabolic Studies of Bile Acids XX. ‘3β-Hydroxysterol Dehydrogenasers' in Rat Liver I. Activity and Fractionation of Rat Liver Homogenate*

Abstract
The enzyme was partially purified by differential centrifugation of the rat liver homogenates (600 and 80,000 G, fractionation of the final supernatant with (NH4)2 SO4 (0.3 and 0.65 saturation), and dialysis. The enzyme catalyzed the dehydrogenative oxidation of 7-[ALPHA]-hydroxycholesterol and cholesterol in the presence of diphosphopyridine nucleotide. None of the 3-er-hydroxy steroids and 3-[BETA]-hydroxy C19- and C21- steroids were oxidized.