Effective reduction of antigenicity of hen egg lysozyme by site-specific glycosylation

Various mutant lysozymes were constructed by genetic modification and secreted in yeast expression system to evaluate the changes in the antigenicity of hen egg lysozyme (HEL). Although Arg68, the most critical residue to antigenicity of HEL, was substituted with Gln, the binding of monoclonal antibodies (mAbs) with the mutant lysozyme did not critically reduce, remaining 60% of the binding with mAb. In contrast, glycosylated mutant lysozyme G49N whose glycine was substituted with asparagine dramatically reduced the binding with mAb. The oligomannosyl type of G49N lysozyme reduced binding with mAb to one-fifth, while the polymannosyl type of G49N lysozyme completely diminished the binding with mAb. This suggests that the site-specific glycosylation of lysozyme in the interfacial region of lysozyme-antibody complex is more effective to reduce the antigenicity than the mutation of single amino acid substitution in the interfacial region.