MAPPING OF AN ALLERGENICALLY IMPORTANT DETERMINANT OF GRASS GROUP-I ALLERGENS

This report documents the mapping of the second major epitope, previou sly described as site D, of grass group I allergens to residues 23-35 of meadow fescue group I (STFYGKPTGAGPK). Mapping was accomplished by screening fractions from a meadow fescue group I tryptic digest for pe ptide(s) that inhibit the ability of monoclonal antibody 24.64 (specif ic for site D) to bind to immobilized group I allergen. One such pepti de, representing residues 23-35 of meadow fescue group I, was identifi ed. Additional studies with the use of synthetic analogs of this pepti de demonstrate that it binds mAb 24.64 directly. Examination of extrac ts containing group I glycoproteins from seven other species of grass confirms antigenic cross-reactivity due to this peptide. We also repor t based on protein sequence analysis that the amino terminal segment ( which includes the site D epitope) of GpI allergens from seven differe nt grass species is highly conserved and contains two hydroxyproline r esidues and an N-linked carbohydrate moiety.