Membrane-bound metalloprotease which catalyzes the removal of a penultimate prolyl residue from the N-termini of peptides, such as Arg-Pro-Pro. May play a role in the metabolism of the vasodilator bradykinin. Release of any N-terminal amino acid, including proline, that is linked to proline, even from a dipeptide or tripeptide. Inhibited by the chelating agents 1,10-phenanthroline and EDTA. Inhibited by the thiol-containing compounds 2-mercaptoethanol and dithiothreitol. Also inhibited by apstatin, captopril and p-(ch1oromercuri)benzenesulfonic acid. Weakly inhibited by D,L-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid and N-[l-(R,S)-carboxy-(2-phenylethyl)]-Ala-Ala-Phe-p-aminobenzoate. Inhibited by ramiprilat and enalaprilat, in a Mn(2+)-dependent manner. Metal ions have a complex substrate- and concentration-dependent effect on activity. Activity towards Arg-Pro-Pro and Gly-Pro-Hyp is stimulated by Mn(2+) ion concentrations of 10-100 uM and then inhibited at Mn(2+) concentrations of 1-2 mM. Mn(2+) concentrations in excess of 2 mM stimulate activity towards Gly-Pro-Hyp but inhibit activity towards Arg-Pro-Pro. Zn(2+) and Co(2+) ions also inhibit activity towards Arg-Pro-Pro at high concentrations. Activity towards bradykinin is inhibited by Mn(2+) concentrations in excess of 1 mM. Optimum pH is 7.0 for bradykinin. Active between pH 6.0-11.0. Thermostable to 55 degrees Celsius. Complete loss of activity above 70-75 degrees Celsius. Homotrimer. Expressed strongly in lung, liver and heart, and at lower levels in kidney, testis, brain, spleen and skeletal muscle. N-glycosylated. Belongs to the peptidase M24B family.