Molecular enzymology of human liver cytosolic sulfotransferases.

Sulfoconjugation of drugs and small xenobiotic and endogenous compounds in human tissues is primarily catalysed by cytosolic forms of sulfotransferase. In most instances, sulfate conjugation is associated with a decrease in the biological activity and an increase in the excretion of the sulfated compounds. However, sulfation may also be involved in the bioactivation of both therapeutic drugs and carcinogens. Two isoenzymes of phenol sulfotransferase and one steroid/bile acid sulfotransferase have been isolated from human liver cytosol. Biochemical and immunological characterization of these proteins has provided insights into their structural similarities, tissue localization and possible biological functions.