EN
Purified proline-specific amino peptidases from Lactobacillus curvatus and from Lactococcus lactis were active on both X-proline dipeptidyl aminopeptidase (PepX) substrates, Gly-Pro-AMC or Gly-PropNA and on proline endopepetidase (PEP) substrates Suc-Gly-Pro-Leu-Gly-Pro, Suc-Gly-Pro-AMC, Z-Gly-Pro-AMC or Suc-Gly-Pro-pNA, however; activity on PEP substrates was markedly less than that on PepX substrates. The enzymes from Lactobacillus and Lactococcus hydrolyzed a number of oligopeptides containing 7-11 amino acids residues and proline at the penultimate position from N-terminus, but hydrolysis of natural PEP oligopeptide substrates containing proline residues at internal positions was negligible. The two proline-specific enzymes were strongly stimulated by NaCl and inhibited by phenylmethylsulfonyl fluoride and organic solvents.