Synergistic action of an X-prolyl dipeptidyl aminopeptidase and a non-specific aminopeptidase in protein hydrolysis

Non-specific monoaminopeptidase (AP; E.C. 3.4.11) and X-prolyl dipeptidyl a minopeptidase (X-PDAP; E.C. 3.4.14.5), both from Aspergillus oryzae, demons trate strong synergism in hydrolyzing proline-containing peptides. Incubati on of AP alone with the peptide Ala-Pro-Gly-Asp-Arg-Ile-Tyr-Val-His-Pro-Phe does not generate free amino acids. However, when AP and X-PDAP are added in combination, complete and immediate hydrolysis of all peptide bonds, oth er than X-pro bonds, is observed. In the enzymatic hydrolysis of casein, so y, and gluten, degree of hydrolysis (DH) values of 54, 54, and 47% were ach ieved, respectively, when subtilisin (E.C. 3.4.21.62) was supplemented with AP. Addition of a third enzyme, X-PDAP, resulted in significantly higher D H values of 69, 72, and 64%, respectively, establishing the utility of this synergism in protein hydrolysis.