Investigation on the binding interaction between rice glutelin and epigallocatechin-3-gallate using spectroscopic and molecular docking simulation

The interaction between plant protein and polyphenol is a topic of considerable interest. However, there is relatively little understanding about the interaction between rice protein and epigallocatechin-3-gallate (EGCG). The spectroscopy and computational docking program were used to investigate the potential interaction between rice glutelin (RG) and EGCG. It was found that the intrinsic fluorescence of RG could be quenched by EGCG, which indicated interaction occurred between them. Thermodynamic analysis elucidated that the interaction process between RG and EGCG happened spontaneously with hydrogen bond as the primary driving force. The ANS-fluorescence indicated that the surface hydrophobicity of RG reduced with the increasing of EGCG. Circular dichroism spectra and synchronous fluorescence gave further information for the conformational and microenvironmental changes of RG. Particularly, the α-helix structure reduced and random coil structure increased after the binding interaction. Furthermore, the computational docking program exhibited target sites in which the amino acid residues of RG and EGCG might be bound together.