Dipeptidase that catalyzes the hydrolysis of dipeptides with a prolyl (Xaa-Pro) or hydroxyprolyl residue in the C-terminal position. The preferred dipeptide substrate is Gly-Pro, but other Xaa-Pro dipeptides, such as Ala-Pro, Met-Pro, Phe-Pro, Val-Pro and Leu-Pro, can be cleaved. Plays an important role in collagen metabolism because the high level of iminoacids in collagen.