Biochemical characterization and thermostable capacity of parvalbumins: The major fish-food allergens

The major allergens in fish-food are parvalbumins (PVs). Muscle PVs of four fish species of genus Channa: Channa gachua, Channa punctatus, Channa striatus and Channa marulius were purified, characterized and used to differentiate (heated) fish specimens. Two to three proteins have been detected as PV-isoforms by immunological probing through Western blotting. They were purified to homogeneity on diethyl amino ethyl-cellulose. Modified systems of nondenaturing and denaturing polyacrylamide gel electrophoresis were used to resolve low molecular weight proteins, distinctly. Isoelectric points (pIs) were determined on native isoelectric focusing gels, which lie in the pI range of 4.55-5.10. The electrophoretic profiles remained species-specific even after heating the PVs for 3 h at 90C and would be of immense help in discerning cooked fish specimens. Further, the addition of 5 mM beta-mercaptoethanol in the PVs has showed protection against heat denaturation of the protein and resulted in more compatible protein patterns. This study also demonstrates the relevance of the thermostable capacity of PVs in the differentiation of heat-processed fish through electrophoretic analysis of heated PVs. Also, they represent a promising and simple biochemical tool in discerning closely related species.