Role of galloyl moiety in modulating the interaction between Cyperus esculentus protein and tea polyphenols: A...

This study explored the role of the galloyl moiety (GM) in protein-polyphenol interactions by examining the binding between Cyperus esculentus protein (CEP) and six tea polyphenols (TPs). Fluorescence quenching results indicated that TPs statically bound to CEP, and the quenching constants of galloylated catechins (CGMs) were significantly higher than non-galloylated counterparts (Cs), suggesting that GM groups enhance the binding affinity. Spectral analyses revealed that CGMs induced the protein α-helix content decreased and β-sheet and random coil structures increased. Surface plasmon resonance and thermodynamic analyses confirmed that the GM groups promote specific binding through hydrogen bonding and hydrophobic interactions. Furthermore, galloylation facilitated larger complexes formation with higher surface charge density, significantly affecting the system turbidity, solubility, and emulsifying properties. This study clarified the differential regulatory effects of CGMs and Cs on the structure, binding affinity, and thermodynamic behavior of CEP, providing theoretical guidance for the precise design of protein-polyphenol composite systems.