Comparative study of binding interactions between different dietary flavonoids and soybean β-conglycinin and glycinin: Impact on structure and function of the proteins

Abstract

The mechanisms underlying the interaction between different dietary flavonoids and soybean β-conglycinin (7S) and glycinin (11S) were comparatively investigated, and the alterations in conformation and function of the complexes were further evaluated. Among the 23 flavonoids studied, 3 flavonoids with glycosides with the top three ranked T Scores in molecular docking analysis-phlorizin, luteoloside, and vitexin-4'-O-glucoside-with the highest binding affinity to 7S and 11S and quenched their intrinsic fluorescence in a static manner. The binding interactions of these flavonoids to 7S and 11S were structure dependent. Hydrophobic forces played important roles in interactions between 7S and both luteoloside and vitexin-4'-O-glucoside, whereas the binding of phlorizin to 7S, and of the three flavonoids to 11S, was driven by hydrogen bonding and van der Waals forces. The binding of these flavonoids interfered with the microenvironment around tyrosine and tryptophan, thereby altering the secondary structures of 7S and 11S. The binding of the three flavonoids enhanced solubility, emulsifying properties, thermal stability, and antioxidant capacity of 7S and 11S. The use of flavonoids could facilitate the design of soybean protein-based products with desirable functional properties.

Keywords: Antioxidant; Binding interaction; Emulsification; Flavonoid; Fluorescence spectroscopy; Molecular docking; Soybean protein.