Identification of IgE-Binding Peptides Derived from Chemical and Enzymatic Cleavage of Ovomucoid (Gal d 1)

Abstract

Ovomucoid (OM), a major allergen of hen's egg white, consists of three trypsin inhibitory domains comprising 186 amino acids. In order to identify IgE-binding sites of its protein backbone OM was cleaved chemically and enzymatically. In SDS-PAGE/immunoblot experiments 10 peptides showing IgE-binding from human sera of egg allergic individuals were identified by amino acid sequencing. Up to five and six out of six sera reacted with peptides derived from trypsin and cyanogen bromide cleavage, respectively. Peptides derived by pepsin and thermolysin cleavage were detected by one and two sera, respectively. A total of five different N-terminal sequences of IgE-binding peptides from OM were determined. At least two distinct epitopes located on regions OM 90-121 and OM 134-186 were identified. The comparison of known antigenic regions from OM with three prediction algorithms revealed 3746% probability for correct prediction. (Internet Symposium on Food Allergens 1999, 1(1):1-12) food allergy egg white ovomucoid chemical and enzymatic cleavage epitope mapping IgE-binding SDS-PAGE/immunoblot amino acid sequencing antigenicity prediction