Apparent dipeptidyl peptidase activities of acylamino acid-releasing enzymes.
An acylamino acid-releasing enzyme purified from porcine liver showed peptidase activity above pH 8. Of the non-acylated peptides tested, this peptidase activity was only exerted on peptides with Gly or Ala at their N-termini. These results are consistent with the previous observations for similar enzymes from sheep red blood cells (Witheiler, J. & Wilson, D.B. (1972) J. Biol. Chem. 247, 2217-2221) and beef liver (Gade, W. & Brown, J.L. (1978) J. Biol. Chem. 253, 5012-5018). The pH dependence of the peptidase activity showed that only peptides with uncharged N-terminal amino acids such as glycyl- or alanyl-peptides act as substrates for the enzyme. These results suggest that the peptidase activity seen for the acylamino acid-releasing enzyme is an intrinsic activity of the enzyme that is triggered by misrecognition of uncharged smaller N-terminal amino acids in non-acylated peptides as acyl groups at higher pHs.
D000818:Animals; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008099:Liver / Q000201:enzymology; D010447:Peptide Hydrolases / Q000378:metabolism*; D013552:Swine
D010450:Endopeptidases; D010447:Peptide Hydrolases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C038220:acylaminoacyl-peptidase