Spectrofluorimetric and molecular docking studies on the interaction of cyanidin-3-O-glucoside with whey protein, β-lactoglobulin

The interaction of beta-Lactoglobulin ((beta-Lg) with cyanidin-3-O-glucoside (C3G) was characterized using fluorescence, circular dichroism spectroscopy, and docking studies under physiological conditions. Fluorescence studies showed that beta-Lg has a strong binding affinity for C3G via hydrophobic interaction with the binding constant, K-a, of 3.14 x 10(4) M-1 at 298 K. The secondary structure of beta-Lg displayed an increase in the major structure of beta-sheet upon binding with C3G, whereas a decrease in the minor structure of alpha-helix was also observed. In addition, evidenced by near UV-CD, the interaction also disrupted the environments of Trp residues. The molecular docking results illustrated that both hydrogen bonding and the hydrophobic interaction are involved as an acting force during the binding process. These results may contribute to a better understanding over the enhanced physicochemical proprieties of anthocyanins due to the complexation with milk proteins. (C) 2017 Elsevier B.V. All rights reserved.