Studies on a 3beta-hydroxysteroid sulphotransferase from rat liver.
A steroid sulphotransferase (EC 2.8.2.2) was partially purified from female rat liver. The enzyme was active towards the substrates, dehydroepiandrosterone, epiandrosterone and pregnenolone but was inactive towards oestrogens, cholesterol and ergocalciferol. A pH optimum of 5.0 was recorded but the enzyme was unstable at low pH. The enzyme was stimulated slightly by the addition of reducing agents and inhibited by p-chloromercuribenzoate and HgCl2. Crude enzyme activity was markedly stimulated by divalent cations but this effect was not observed with purified enzyme. A Km of 13 muM was calculated for the donor substrate 3'-phosphoadenylyl sulphate and the acceptor substrate, dehydroepiandrosterone had a Km value of 6 muM. The enzyme appeared to be highly susceptible to product inhibition by adenosine 3', 5'-diphosphate.
D000818:Animals; D002729:Chloromercuribenzoates / Q000494:pharmacology; D003687:Dehydroepiandrosterone / Q000494:pharmacology; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008628:Mercury / Q000494:pharmacology; D051381:Rats; D013329:Structure-Activity Relationship; D013466:Sulfurtransferases / Q000302:isolation & purification / Q000378:metabolism*
D002729:Chloromercuribenzoates; D003687:Dehydroepiandrosterone; D013466:Sulfurtransferases; D008628:Mercury