Partial characterization of steroid sulfohydrolase and steroid sulfotransferase activities in purified porcine Leydig cells

Subcellular fractions of purified pig Leydig cells from 7 different animals have been investigated with respect to their abilities to catalyze the sulfation of several steroids and the hydrolysis of the sulfated forms of these same steroids. Considerable estrone sulfate sulfohydrolase of pH optimum 7.5 and high apparent Km was found to be concentrated in the 105,000 g pellet but no evidence was obtained, in any subcellular fraction, for the presence of any activity toward the 3-sulfate of pregnenolone, dehydroepiandrosterone (DHA) or delta 5-androstene-3 beta,17 beta-diol (androstenediol). Cytosolic sulfotransferase activity toward estrone, pregnenolone, DHA and androstenediol was present in each animal. The activity toward these 4 substrates was eluted from a gel filtration column as a single peak of apparent molecular weight 43 KDa. Upon chromatofocusing, a sharp estrogen sulfotransferase peak of apparent pI 6.1 and pH optimum 9.5, was clearly separated from the neutral steroid sulfotransferase which eluted over a more acidic pH range in a manner suggestive of the presence of several isozymes. This latter, which exhibited a wide pH optimum range between 6 and 8.5, was most active toward androstenediol, and least active toward pregnenolone. The estrogen sulfotransferase exhibited Michaelis-Menten kinetics (apparent Km = 4 microM). The neutral steroid sulfotransferase activity increased in velocity with increasing androstenediol or DHA concentration up to 1 microM beyond which considerable substrate inhibition occurred. It appears from these data that neutral steroid sulfates synthesized in the pig Leydig cell are not subject to enzymic desulfation in the same cells.