Investigation of the interaction between (-)-epigallocatechin-3-gallate with trypsin and α-chymotrypsin

Tea polyphenol (TP) inhibits digestive enzymes and reduces food digestibility. To explore the interaction between TP with digestive enzymes, bindings of -epigallocatechin-3-gallate (EGCG) to trypsin and -chymotrypsin were studied in detail using fluorescence, resonance light-scattering, circular dichroism, fourier transform infrared spectroscopy methods and protein-ligand docking. The binding parameters were calculated according to Stern-Volmer equation, and the thermodynamic parameters were determined by the van't Hoff equation. The results indicated that EGCG was capable of binding trypsin and -chymotrypsin with high affinity, resulting in a change of native conformation of these enzymes. EGCG had a greater influence on the structure of -chymotrypsin than trypsin. This study can be used to explain the binding interaction mechanism between TP and digestive enzymes.