Interaction and binding mechanism of cyanidin-3-O-glucoside to lysozyme in varying pH conditions: Multi-spectroscopic, molecular docking and molecular dynamics simulation approaches

Due to pH sensitivity, the interaction between lysozyme and cyanidin-3-O-glucoside was investigated at pH 3.0 and 7.4 via multi-spectroscopic approaches, with additional molecular docking and molecular dynamics simulation (MD). Binding with cyanidin-3-O-glucoside, the enhanced UV spectra and the reduced the α-helicity of lysozyme were both more significant at pH 7.4 than that at pH 3.0 (p < 0.05), corresponding to Fourier transform infrared spectroscopy (FTIR) study. Fluorescence quenching indicated the static mode was major at pH 3.0 with a part dynamic mode at pH 7.4 with a significantly high of Ks at 310 K (p < 0.05), corresponding to their MD. An instantaneous conformation of lysozyme was observed during C3G addition at pH 7.4 in fluorescence phase diagram. Cyanidin-3-O-glucoside derivatives bind with lysozyme at a common site via hydrogen-bond and π-π interactions in molecular docking and tryptophan played a potential role in the interaction based on the MD.