Interaction between Coomassie Brilliant Blue and hen egg white lysozyme: Insights from molecular docking, simulation,...

This study investigates the interaction between Coomassie Brilliant Blue (CBB) dye and Hen Egg White Lysozyme (HEWL) through a combination of molecular docking, molecular dynamics (MD) simulations, intrinsic fluorescence spectroscopy, and Fourier Transform Infrared (FTIR) spectroscopy. Molecular docking revealed a moderate binding affinity of (-3.55 J/mol), with key interactions involving Arg73 and Arg112 residues. MD simulations conducted over 100 ns demonstrated enhanced structural stability of the HEWL-CBB complex compared to the native protein. Analysis of the secondary structure of HEWL indicated that CBB binding promotes the formation of coil structures, contributing to secondary structure alterations. Fluorescence quenching analysis revealed a static quenching mechanism with a 1:2 binding stoichiometry. Thermodynamic parameters indicated that the interaction is endothermic and entropy-driven, as evidenced by positive values of enthalpy (ΔH⁰) and entropy (ΔS⁰), along with negative Gibbs free energy (ΔG⁰) values that became increasingly negative with rising temperature, confirming the spontaneity of the interaction. The role of electrostatic forces in HEWL-CBB binding was further validated through salt interference experiments using ammonium sulfate. FTIR spectroscopy supported these findings, revealing noticeable shifts in the amide I and amide II bands, indicative of conformational changes in HEWL's secondary structure upon CBB binding. Collectively, these results provide a detailed understanding of the moderate yet specific interaction between HEWL and CBB, highlighting its potential utility in dye-ligand affinity chromatography applications.