Interaction of glycosylated legumin with EGCG and quercetin: structure and stability analysis

Polyphenols have a strong binding capacity with proteins, but the binding behavior of polyphenols with glycosylated proteins and the effects of binding on the structure of glycosylated proteins have been less studied. This study used enzymatic modification to prepare an oligochitosan-legumin complex (OLC) to investigate its interaction with (-)-epigallocatechin gallate (EGCG) and quercetin. Fluorescence spectroscopy experiments showed that the binding site of OLC to EGCG was 27.7 ± 2.47 and that of quercetin to OLC was 19.5 ± 2.92; the binding of one polyphenol affected the other's ability to bind to OLC. The FTIR and CD results showed secondary structural changes in OLC after incorporating polyphenols, with a decrease in the content of α-helix and an increase in the content of β-sheet. The OLC and OLC-polyphenol complexes showed smaller particle size and denser micromorphology. Moreover, OLC had a protective effect on EGCG and quercetin against thermal and ultraviolet light treatments compared to polyphenols alone. Transglutaminase was used to catalyze the crosslinking of legumin and oligochitosan. The interaction between OLC and two polyphenols with different properties was studied, and OLC was successfully developed as a carrier to protect two bioactive substances. This study demonstrated the interaction mechanism between glycosylated proteins and polyphenols, providing a basis for the application of glycosylated proteins in encapsulation, protection, and delivery of bioactive substances. © 2025 Society of Chemical Industry.