Lactococcus X-Pro dipeptidyl-peptidase proteins (X-PDAP) belong to the S15 family of the carboxypeptidase (SC) clan. These proteins, which have similar pecificity to mammalian dipeptidyl-peptidase IV, cleave Xaa-Pro-releasing N-terminal dipeptides. The penultimate residue must be proline. In Lactococcus, the proteins exist as cytoplasmic homodimers. The closest relative is Cocaine_esterase