Interaction of Isoflavones with β-Conglycinin and Its Effect on the Structure and Potential Allergenicity of Their Complex

In this study, the interaction mechanism of isoflavones with β-conglycinin (BGG) and its effect on the structure and potential allergenicity of their complex were investigated. Fluorescence spectroscopy and circular dichroism spectroscopy were used to analyze the types of quenching, the number of binding sites, the types of forces and the secondary structure content of BGG complexes with one of the two soy isoflavones genistein (Gen) and daidzein (Dai). The structure of isoflavone-BGG complexes prepared under different conditions was characterized, and the potential allergenicity of the complexes were detected by enzyme linked immunosorbent assay (ELISA) and Western blotting. The result showed that isoflavones caused a static quench of the fluorescence of BGG, and the interaction was dominated by hydrophobic interactions, with one binding site. Furthermore, the interaction with isoflavones induced an increase in the polarity of the amino acid microenvironment of BGG, which led to unfolding of the peptide chain and a looser structure. ELISA and immunoblotting of digestion products showed that the potential allergenicity of the protein was enhanced by the binding of isoflavones. The results of this study would be helpful to understand how isoflavones affect the allergenicity of allergenic proteins in complex food matrices, and be significant for its further development and utilization for allergenicity reduction.