Catalyzes the removal of a penultimate prolyl residue from the N-termini of peptides, such as Arg-Pro-Pro. Release of any N-terminal amino acid, including proline, that is linked to proline, even from a dipeptide or tripeptide. Inhibited by the chelating agent EDTA. Divalent metal ions have substrate- and concentration-dependent effects on activity. Activity towards bradykinin is inhibited with increasing Mn(2+) concentration. Activity towards substance P is stimulated by low Mn(2+) concentrations (in the range 10 uM-1 mM) but inhibited by Mn(2+) concentrations in excess of 1 mM. Ca(2+), Mg(2+) and Co(2+) stimulate activity towards substance P at concentrations of 10-100 uM but are inhibitory at concentrations of 1 mM. Zn(2+), Ni(2+) and Cu(2+) strongly inhibit activity towards substance P at concentrations of 1 mM. Optimum pH is 7.6. Detected in gut, brain, testes and ovary. Expressed in embryos from 9-22 hours, but not detected in first and second instar larvae. Expressed in 3rd instar larvae and at high levels in pupae. Belongs to the peptidase M24B family.