Enzymatic sulfation of steroids. XIX. Cortisol sulfotransferase activity, glucocorticoid sulfotransferases, and tyrosine aminotransferase induction in chicken, gerbil, and and hamster liver

Abstract

Radioisotopic, pH 6.8 assays were designed to measure hepatic cortisol sulfation in chickens, gerbils, and hamsters of both sexes. Enzyme levels with 40 μM cortisol were similar in males of all three species and due mostly to low Km enzymes with 10–30 μM cortisol Km's. Maximum enzyme activity in male chickens required 40 μM Cortisol. In the other species, the much higher maximum enzyme activity observed required 500 μM cortisol owing to sulfotransferases with Km's for the hormone near 300 μM. Coenzyme 3′-phosphoadenosine-5′-phosphosulfate requirements also varied between species. Sex differences of the enzyme levels were found only in hamsters. There, males possessed only 24–33% of the enzyme levels found in females. Cortisol 21-sulfate was the reaction product in all of the species. Sexual dimorphism in hamsters appeared to be due to repressive effects of androgens. pH optima of enzyme activities in the three species ranged from pH 6 to 7. Routine use of pH 6.8 assays allowed representative interspecies comparisons. DEAE-Sephadex fractionation of cytosol showed that chicken liver contained mostly two enzymes with different pH optima that catalyzed cortisol sulfation. These differed from the enzymes that catalyzed dehydroepiandrosterone and estradiol sulfation. In the gerbil four enzymes with similar pH optima catalyzed cortisol sulfation. The second of these to elute from DEAE-Sephadex columns was the low Km form. In hamsters most glucocorticoid sulfotransferase activity appeared to be due to one enzyme. The molecular weights of the low Km gerbil enzyme and the main hamster enzyme were 98 300 ± 6100 and 105 000 ± 8100. Hamsters and gerbils responded to injection of cortisol by hepatic tyrosine aminotransferase induction.