Hydrolyzes L-prolinamide, L-proline-p-nitroanilide, L-alaninamide, L-methioninamide, piperidine-2-carboxamide and piperazine-2-carboxamide. Has a much lower activity towards piperazine-2-tert-butylcarboxamide. Does not hydrolyze dipeptides and D-prolinamide. (S)-piperazine-2-carboxamide + H2O = (S)-piperazine-2-carboxylate + NH4(+) H2O + L-prolinamide = L-proline + NH4(+) Completely inhibited by ZnSO(4), ZnCl(2), AgNO(3), CdCl(2) and HgCl(2). Partially inhibited by PbCl(2), NiCl(2) and CoCl(2). Unaffected by LiBr, H(2)BO(3), NaCl, MgSO(4), AlCl(3), KCl, CaCl(2), CrCl(3), MnCl(2), FeSO(4), Fe(NH(4))(2)(SO(4))(2), CuSO(4), RbCl, Na(2)MoO(4), (NH(4))(6)Mo(7)O(24), SnCl(2), CsCl and BaCl(2). Completely inhibited by phenylhydrazine, but not by the other carbonyl reagents hydroxylamine, hydrazine, D,L-penicillamine and D-cycloserine. Unaffected by the chelating agents o-phenanthroline, 8-hydroxyquinoline, enthylenediaminetetraacetic acid and alpha,alpha'-dipyridyl. Partially inhibited by the thiol reagents p-chloromercuribenzoate, iodoacetate and N-ethylmaleimide. Not affected by the serine protease inhibitor phenylmethanesulfonyl fluoride, the serine/cysteine protease inhibitor leupeptine or the aspartic protease inhibitor pepstatin. Monomer. Belongs to the peptidase S33 family.