5 beta-Scymnol sulfotransferases from the liver of two Australian ray species

The tissue distribution of sterol sulfotransferase activity was investigate d within the ray species Trygonorrhina fasciata and Trygonoptera species. T he liver and kidney cytosolic fractions of each species were found to conta in an enzyme that catalyzed the transfer of the sulfonate group from 3'-pho sphoadenosine 5'-phosphosulfate to the elasmobranch bile alcohol 5 beta-scy mnol. The liver is the major site of bile salt biosynthesis and detoxicatio n, with the kidney possibly playing a secondary role. The two ray species l iver sulfotransferases were partially purified by column chromatography and characterized. The enzymic properties of the partially purified liver sulf otransferases from the T. fasciata and Trygonoptera sp. ray species were si milar in character. They followed Michaelis-Menten kinetics and were inhibi ted by the substrate 5 beta-scymnol and the reaction product adenosine-3',5 '-diphosphate. The enzymes were activated by the addition of magnesium ions , but had no absolute requirement for these ions; however, they were found to require sulfhydryl groups for activity. The steroid alcohols 5 beta-scym nol and 5 alpha-cyprinol were both substrates for the sulfation reaction an d the enzymes showed pH optimums of about 6.5, with a range of 5.5-7.5 and a temperature range from 22 to 37 degrees C. This is the first report conce rning sulfotransferase activity in ray species. (C) 1998 Elsevier Science I nc. All rights reserved.