Enzymic synthesis of steroid sulphates. XIV. Properties of human adrenal steroid alcohol sulphotransferase.
Pure steroid alcohol sulphotransferase (EC 2.8.2.-) has the property of sulphurylating hydroxyl groups on different positions of the steroid ring. It has now been established that although only monosulphates are formed from substrates such as 3,17-diols, the position of the sulphate group depends on the relative configuration of the hydroxyl groups. Androst-5-ene-3 beta,17 beta-diol, for example, is sulphurylated mainly at the 17-position. In addition, compounds such as epitestosterone and 17 alpha-estradiol are sulphurylated at much higher rates than their respective 17 beta-epimers. It is believed that the steroid can approach the sulphurylation site via (i) ring A with the beta-side upwards, and in this mode a 3 beta-hydroxyl is sulphurylated at a higher rate than a 3 alpha-hydroxyl, or (ii) ring D with the beta-side downwards, and in this mode a 17 alpha-hydroxyl group is oriented in an analogous fashion to the 3 beta-hydroxyl in (i). The enzyme exhibits non-Michaelis-Menten kinetics within physiological concentrations (0-2 micro M) of the substrate dehydroepiandrosterone and evidence was obtained for the presence of multiple interacting steroid-binding sites. A regulatory role for the enzyme in the secretion of dehydroepiandrosterone from the human adrenal gland is proposed.
D000311:Adrenal Glands / Q000201:enzymology*; D015114:Androstenediol / Q000378:metabolism; D002413:Cations, Divalent; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate; D004355:Drug Stability; D006801:Humans; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D008968:Molecular Conformation; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D015238:Sulfotransferases; D013466:Sulfurtransferases / Q000378:metabolism*
D002413:Cations, Divalent; D008670:Metals; D013439:Sulfhydryl Reagents; D003687:Dehydroepiandrosterone; D019314:Dehydroepiandrosterone Sulfate; D015114:Androstenediol; D013466:Sulfurtransferases; D015238:Sulfotransferases; C028152:alcohol sulfotransferase