Digestion of atopic allergens with trypsin α-chymotrypsin and pancreatic kallikrein, and influence of the allergens upon the proteolytic and esterolytic activity of these enzymes

Abstract

The action of bovine trypsin, α-chymotrypsin and pancreatic kallikrein upon a number of atopic allergens has been studied by pH-stat measurements during short-term incubation. Most atopic allergens proved chemically resistant towards these enzymes. Graphs of enzyme susceptibility vs. the ratio of extinction coefficients E305/E280, or against the per centage of available lysine, suggest that the liability of allergens to proteolysis depends on the number of 1-deoxy-2-ketoses linked to the ε-amino groups of lysine residues in the peptide moieties. This relationship is further exemplified with results obtained with a number of well-defined synthetic model proteins incorporating different proportions of N-conjugated sugar. The allergens were found to be competitive inhibitors of the proteolytic activity of trypsin and chymotrypsin, but not of kallikrein. Evidence was obtained for an additional element of non-competitive inhibition in the case of trypsin. The esterolytic activity of three enzymes proved to be unimpaired in the presence of allergens.