Cysteate synthase

Cysteate synthase (EC 2.5.1.76) is an enzyme characterised from Methanosarcinales with systematic name sulfite:O-phospho-L-serine sulfotransferase (phosphate-hydrolysing, L-cysteate-forming).^[1] It catalyses the following chemical reaction which produces L-cysteic acid by reacting phosphoserine with sulfite (H₂SO₃), giving orthophosphate (P_i) as a byproduct:^[2]

This enzyme is a transferase containing pyridoxal-phosphate as a cofactor.^[1]