Elucidation of a major IgE epitope of Pacific mackerel parvalbumin

Ten overlapping peptides (20 amino acids in length with an offset of 10 amino acids) spanning the amino acid sequence of Pacific mackerel, Scomber japonicus parvalbumin (Sco j 1), were synthesized and evaluated for IgE-binding ability by fluorescence ELISA using fish-allergic patient sera. As a result, the region 21–40 was judged to contain a major IgE epitope of Sco j 1. However, this region was not necessarily assumed to be a major IgE epitope for the parvalbumins from seven other species of fish (sardine, Japanese eel, cod, horse mackerel, crimson sea bream, skipjack and flounder). Ala-scanning experiments revealed that eight amino acid residues (Ser-23, His-26, Lys-27, Lys-28, Lys-31, Cys-33, Leu-35 and Lys-38) are important for the IgE-binding of Sco j 1. Some of these residues are replaced by different residues in the parvalbumins of the other seven species of fish.