Peptidase M14 carboxypeptidase subfamily A/B-like; Carboxypeptidase O subgroup
Peptidase M14 carboxypeptidase (CP) O (CPO, also known as metallocarboxypeptidase C; EC 3.4.17.) belongs to the carboxypeptidase A/B subfamily of the M14 family of metallocarboxypeptidases (MCPs). The M14 family are zinc-binding CPs which hydrolyze single, C-terminal amino acids from polypeptide chains, and have a recognition site for the free C-terminal carboxyl group, which is a key determinant of specificity. CPO has not been well characterized as yet, and little is known about it. Based on modeling studies, CPO has been suggested to have specificity for acidic residues rather than aliphatic/aromatic residues as in A-like enzymes or basic residues as in B-like enzymes. It remains to be demonstrated that CPO is functional as an MCP.
Comment:Metallocarboxypeptidases share the zinc binding motif HXXE...H, where the zinc ion is penta-coordinated to ND1 atoms of the histidines, OE1 and OE2 atoms of the glutamic acid, and to a water molecule in a slightly distorted tetrahedral manner.
Jiyao W et al.(2023). "The conserved domain database in 2023.",