Surface plasmon resonance, molecular docking, and molecular dynamics simulation studies of lysozyme interaction with tannic acid.

Lysozyme (L) is an important enzyme in medicine and industry. Tannic acid (TA) is used in brewing, wine industry, and as a food flavor enhancer. In nutritional and food science, L interacts with TA, notably in wine and saliva. This study aimed to investigate the binding interaction between L and TA using surface plasmon resonance, molecular docking, and molecular dynamics simulation. Chicken egg white lysozyme (CEWL) was applied as a model protein. Tri-N-acetylchitotriose (NAG), the known inhibitor of CEWL, was used in the redocking experiments to determine the precise binding location within the complex. The average binding energies obtained from docking NAG and tannic acid to the target structure of CEWL were found to be -6.46 ± 0.05 kcal/mol and -7.52 ± 0.39 kcal/mol, respectively. The binding free energy of the CEWL-TA complex was then calculated as -27.61 kcal/mol by MMPBSA based on MD simulation trajectories. The observed interactions between the ligands and the lysozyme structure were mainly driven by hydrophobic, van der Waals, and H-bond interactions formed by the active site residues. MD simulations showed consistent and satisfactory binding distances between CEWL and TA throughout the analysis. SPR analysis was performed using 1X PBS buffer (pH 7.4) as coupling and running buffers, 30 μL/min as flow rate, and 2.5 mg/mL CEWL. Serial concentrations of TA (20-150 μM) were injected through immobilized CEWL, and the value of CEWL-TA binding was obtained as 4.17 × 10 M. This study could enhance existing literature and pave the way for future research in food science and oral biology.