Kinetic investigation of the hydrolysis of aminoacyl p-nitroanilides by dipeptidyl peptidase IV from human and pig kidney.
Dipeptidyl peptidase IV (dipeptidyl-peptide hydrolase, EC 3.4.14.5), an enzyme that participates in the catabolism of bradykinin and Substance P as well as the post-translational processing of various other peptides, has been purified from human and pig kidney. The assay reaction involved the cleavage of p-nitroaniline (pNA) from various dipeptidyl p-nitroanilides. The specific activities of the human and pig enzyme (with Gly-Pro-pNA at pH 7.6) were 49.2 and 45.8, respectively. The dependence of initial reaction velocity on substrate concentration was determined for a variety of dipeptidyl p-nitroanilides over the concentration range 0.05 to 2.0 mM. Most of the substrates tested produced significant non-hyperbolic behavior for the function v vs. S at concentrations above 0.5 mM. As to differences between the two enzymes, the pig enzyme exhibited featureless (i.e., hyperbolic) behavior with Glu-Pro-pNA concentrations as high as 2.0 mM, whereas the human enzyme produced significant non-hyperbolic behavior for the function v vs. S, beginning at S = 0.4 mM. Thus, the human and pig dipeptidyl peptidases IV are kinetically distinct enzyme forms.
D000813:Anilides / Q000378:metabolism*; D000818:Animals; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008433:Mathematics; D011392:Proline / Q000031:analogs & derivatives*; D013045:Species Specificity; D013552:Swine
D000813:Anilides; D011392:Proline; D010450:Endopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases