STransferase

S-transferase is a term used in biochemistry to refer to enzymes that catalyze the transfer of sulfur-containing groups between molecules. It is not a single enzyme but a functional category that includes several families, most notably the glutathione S-transferases (GSTs) and the sulfotransferases (SULTs).

Glutathione S-transferases catalyze the conjugation of reduced glutathione (GSH) to electrophilic substrates, forming more water-soluble conjugates that can be excreted. Most GSTs function as dimers, with active sites that bind GSH and the substrate at the dimer interface. Catalysis typically involves nucleophilic attack by the glutathione thiolate on the electrophilic substrate, enhancing detoxification and clearance of xenobiotics and metabolites.

Sulfotransferases transfer sulfo groups from 3'-phosphoadenosine-5'-phosphosulfate (PAPS) to acceptor substrates, such as hydroxyl or amine groups, generating sulfate esters or sulfamates. This class operates through mechanisms that activate the sulfate donor and facilitate transfer to the substrate, influencing hormone activity, metabolism, and signaling.

Biological roles of S-transferases include detoxification of drugs and environmental chemicals, metabolism of endogenous compounds, and regulation of physiological processes through sulfation. They are widespread across animals, plants, and microorganisms, with multiple isoforms and tissue-specific patterns of expression.

Clinically and technologically, GST polymorphisms can affect drug responses and toxicant susceptibility, while sulfotransferases impact hormone action and pharmacokinetics. S-transferases are studied for their roles in metabolism, toxicology, and biotechnological applications such as bioremediation and biosensing.

See also: transferase, glutathione S-transferase, sulfotransferase.