Purification, immunological properties and molecular cloning of two allergenic parvalbumins from the crimson sea bream, Evynnis japonica

Parvalbumin, a calcium-binding sarcoplasmic protein of 12 kDa, represents a major allergen of fish. Previous immunoblotting experiments suggested the presence of a 14 kDa allergen, together with parvalbumin, in sea breams. In this study, the 14 kDa allergen (PA I) and parvalbumin (PA II) were purified from the white muscle of crimson sea bream, Evynnis japonica, by gel filtration and reverse-phase HPLC. Amino acid sequencing of lysylendopeptidase peptide fragments demonstrated that both PA I and PA II were isoforms of parvalbumin. As analysed by ELISA, PA I showed weaker reactivities with IgG (monoclonal or polyclonal antibody) and serum IgE in fish-allergic patients than did other fish parvalbumins, including PA II. The amino acid sequences of PA I and PA II were elucidated by cDNA cloning. PA I was found to have more specific amino acid residues at several positions compared to the other fish parvalbumins.