Class II Chelatase: a family of ATP-independent monomeric or homodimeric enzymes that catalyze the insertion of metal into protoporphyrin rings. This family includes protoporphyrin IX ferrochelatase (HemH), sirohydrochlorin ferrochelatase (SirB) and the cobaltochelatases, CbiK and CbiX. HemH and SirB are involved in heme and siroheme biosynthesis, respectively, while the cobaltochelatases are associated with cobalamin biosynthesis. Excluded from this family are the ATP-dependent heterotrimeric chelatases (class I) and the multifunctional homodimeric enzymes with dehydrogenase and chelatase activities (class III).
Comment:Structure has Cu2+ inserted into the porphyrin moiety.
Comment:The active site is located in a cleft between the N- and C-terminal domains. The active site is partially but not completely symmetrical, containing some residues from equivalent positions in both domains. In the case of ferrochelatase, an insert in the N-terminus makes additional contributions to the active site.
Jiyao W et al.(2023). "The conserved domain database in 2023.",