bacterial and archael members of the sulfite oxidase (SO) family of molybdopterin binding domains. This molybdopterin cofactor (Moco) binding domain is found in a variety of oxidoreductases, main members of this family are nitrate reductase (NR) and sulfite oxidase (SO). Common features of all known members of this family are that they contain one single pterin cofactor and part of the coordination of the metal (Mo) is a cysteine ligand of the protein and that they catalyze the transfer of an oxygen to or from a lone pair of electrons on the substrate. The specific function of this subgroup is unknown.
Jiyao W et al.(2023). "The conserved domain database in 2023.",