Cleaves peptide bonds on the C-terminal side of prolyl residues within peptides that are up to approximately 30 amino acids long. Has high activity on the succinyl- (suc-) peptide-4-methylcoumaryl-7-amide (MCA) substrates suc-Gly-Pro-Leu-Gly-Pro-MCA, suc-Gly-Pro-MCA and suc-Ala-Ala-Ala-MCA. Hydrolysis of Pro-|-Xaa >> Ala-|-Xaa in oligopeptides. Inhibited by DFP, Z-Pro-prolinal and poststatin, but not by PMSF, SBTI, EDTA, leupeptin, E-64 and pepstatin. Expressed in all tissues tested: uterus, kidney, heart, lung, small intestine, smooth muscle, liver, spleen, thymus, adrenal, pituitary and whole brain. In the estrous cycle, expression and activity are highest in the luteal phase. Belongs to the peptidase S9A family.