Tropomyosin, the Major Oyster Crassostrea gigas Allergen and its IgE‐binding Epitopes

The major allergen ( Cra g 1) isolated from the oyster Crassostrea gigas was digested with lysylendopeptidase. Twenty‐one peptide fragments were isolated from the digest by reverse‐phase HPLC and some of them were sequenced. Cra g 1 was identified as tropomyosin. In competitive ELISA inhibition analyses of lysylendopeptidase fragments, a peptide (K21) showed maximum inhibition of the binding of IgE antibodies in sensitive human serum to Cra g 1. On further tryptic hydrolysis of K21, two peptides exhibited high inhibitory ability equivalent to K21. These results suggested that Cra g 1 had an IgE‐binding epitope in the segment 92–105 (IQLLEEDMERSEER) which was dissimilar to those of the major allergen (tropomyosin) from the shrimp Penaeus indicus.