Molecular Dynamics Simulation of the Binding Between β-Lactoglobulin and Anthocyanins Under Different Sucrose Concentrations

Abstract:

[Objective] This study aims to investigate the effects of adding sucrose to plant-based beverages containing milk on the structure and properties of milk proteins, as well as the binding of proteins to small molecules in plants. [Method]Molecular dynamics simulation was conducted for the binding patterns between β-lactoglobulin and anthocyanins and the protein structure changes under different sucrose concentrations (0, 0.25, 0.50, 0.75, and 1.00 mol/L). [Result] Anthocyanins mainly bound to the hydrophobic cavity of β-lactoglobulin. With the optimal binding conformation as the starting structure, GROMACS was used for the molecular dynamics simulation at 150 ns. The results showed that the structure of β-lactoglobulin in the sucrose solution was more stable, with milder fluctuations of amino acid residues. The increase in the number of α helixes significantly increased the hydrogen bonds between proteins, which was accompanied by the decrease in the number of β folds. The binding free energy between β-lactoglobulin and anthocyanins did not change much in 0.25 and 0.50 mol/L sucrose environments, but significantly increased in the 0.75 mol/L sucrose solution and significantly decreased in the 1.00 mol/L sucrose solution compared with the control group. The differences in binding free energy were mainly caused by changes in van der Waals forces and hydrogen bonding. [Conclusion] The changes in sucrose concentration would cause the differences of the binding position and binding mechanisms of anthocyanins on the β-lactoglobulin surface.