Influence of thermal treatment on the characteristics of major oyster allergen Cra g 1 (tropomyosin).

BACKGROUND: Shellfish, including oysters, often cause allergic reactions in adults. Thermal treatment is one of the most common technologies for dealing with seafood, which may affect biological properties. The present study aimed to evaluate the impact of heating on the conformation and potential allergenicity of oyster-derived tropomyosin (Cra g 1).

RESULTS: Sodium dodecylsulphate-polyacrylamide gel electrophoresis showed that there was an apparent band at 35 kDa of raw tropomyosin after purification and more significant polymers appeared in the heated protein. Interestingly, obvious changes in the intensity of the circular dichroism signal and 1-anilino-8-naphthalene sulfonate-binding fluorescence were observed especially in the case of the roasted form, which was associated with an increase in antibody reactivity. The degree of immunoglobulin (Ig)E binding of this treatment was demonstrated in the order roasted > boiled > raw. Furthermore, sequence alignment and amino acid composition revealed that Cra g 1 shared relatively high homology to tropomyosins from other shellfish and was also abundant in lysine that was apt to be modified by reducing sugars during heating.

CONCLUSION: Heated Cra g 1 produces higher IgE reactivity than the raw form as a result of the denaturation and formation of polymers. These findings will benefit the diagnosis and management of potential allergenicity as a result of shellfish. © 2018 Society of Chemical Industry.