Partial purification of a human liver sulphotransferase active towards bile salts

An enzyme that catalyzes the transfer of sulphate from 3'-phosphoadenosine 5'-phosphosulphate to bile salts was purified from human liver cytosol by chromatography on DEAE-Sephadex and Sephadex G-200, by agarose suspension electrophoresis and by isoelectric focusing in free solution. The purified enzyme was also active towards oestrone, dehydroepiandrosterone and phenol. No other liver steroid sulphotransferases could be detected during this purification procedure. Km values of 1.8 . 10(-6) M and 3.3 . 10(-6) M for glycolithocholate and 3'-phosphoadenosine 5'-phosphosulphate respectively were found. The sulphotransferase has an isoelectric point of 5.5. The enzyme was markedly activated by Mg2+, Mn2+ and Co2+ and inhibited by Cu2+, Fe2+ and Zn2+. Chenodeoxycholate and deoxycholate were sulphated at the 7-OH and 12-OH position, respectively. No bile salt disulphate formation was detected. A 30-fold increase in specific activity was obtained, although the purification based on ultraviolet light measurements was considerably higher.