Studies on the interaction of -epigallocatechin-3-gallate from green tea with bovine β-lactoglobulin by spectroscopic methods and docking

The binding interaction between-epigallocatechin-3-gallate (EGCG) and bovine β-lactoglobulin (βLG) was thoroughly studied by fluorescence, circular dichroism (CD) and protein-ligand docking. Fluorescence data revealed that the fluorescence quenching of βLG by EGCG was the result of the formation of a complex of βLG-EGCG. The binding constants and thermodynamic parameters at two different temperatures and the binding force were determined. The binding interaction between EGCG and βLG was mainly hydrophobic and the complex was stabilised by hydrogen bonding. The results suggested that βLG in complex with EGCG changes its native conformation. Furthermore, preheat treatment (90°C, 120°C) and emulsifier (sucrose fatty acid ester) all boosted the binding constants (K_a) and the binding site values (n) of the βLG-EGCG complex. This study provided important insight into the mechanism of binding interactions of green tea flavonoids with milk protein.