Characterization of a 36 kDa antigenic protein of fish-specific monoclonal-antibody 8F5

The 36 kDa antigenic protein of a fish-specific monoclonal antibody (mAb), 8F5, previously developed to detect fish in foodstuffs to protect fish allergic individuals, was characterized to establish its identity and to identify the fish-specific epitope. We hypothesized that this antigenic protein is tropomyosin based on its thermal stability and molecular weight. Western blot showed that both the 36 kDa protein and fish tropomyosin were recognized by mAb 8F5, and their molecular weight migration in urea gel electrophoresis was identical. In addition to matching the amino acid composition profile, this 36 kDa protein's sequences precisely correspond to those in fish tropomyosin fragments. Further analysis revealed the sequence of the fish-specific epitope bound by mAb 8F5 to be EDDLVALQKK. These results confirm that the 36 kDa protein is indeed tropomyosin and will be a suitable biomarker for the immunodetection of fish in cooked food.