In biochemistry, sulfotransferases (SULTs) are transferase enzymes that catalyze the transfer of a sulfo group () from a donor molecule to an acceptor alcohol () or amine (). The most common sulfo group donor is  3-phosphoadenosine-5-phosphosulfate (PAPS). In the case of alcohol as acceptor, the product is a sulfate ():
whereas an amine leads to a sulfamate ():
Both reactive groups for a sulfonation via sulfotransferases may be part of a protein, lipid, carbohydrate or steroid.