Sulfotransferase enzymes catalyze the sulfate conjugation of many hormones, neurotransmitters, drugs, and xenobiotic compounds. These cytosolic enzymes are different in their tissue distributions and substrate specificities. Estrogen sulfotransferase may control the level of the estrogen receptor by sulfurylating free estradiol. Recombinant SULT1E1, fused to His-tag at C-terminus, was expressed in E.coli and was purified by conventional chromatography.