Hydrogen-bond induced non-linear size dependence of lysozyme under the influence of aqueous glyceline.

This article focuses on the molecular dynamics simulation study of lysozyme protein stability and conformation in aqueous mixtures of glyceline, a natural deep eutectic solvent (NADES) composed of choline chloride and glycerol. The simulations reveal a non-monotonous dependence of the protein's radius of gyration (Rg) on water concentration, with Rg increasing up to 40 wt.% water and then decreasing at higher dilutions, reflecting reversible conformational changes. Analysis of hydrogen bonding shows that at low water content, a strong glycerol–water hydrogen bond network constrains the protein, while increased water promotes protein–water interactions that expand the protein structure; at higher water levels, interactions with DES components and water again compact the protein. Secondary structure elements remain largely stable across all concentrations, suggesting that aqueous glyceline can preserve protein functionality, highlighting NADESs' potential as environmentally friendly solvents for pharmaceutical and biotechnological applications.