High pressure small-angle neutron scattering study of the aggregation state of β-lactoglobulin in water and in water/ethylene-glycol solutions

High-pressure SANS experiments have been performed on acidic dilute solutions of the dimeric protein β-lactoglobulin. To evidence the solvent effect on the protein stability during compression, two different solvents, D2O and a 50% w/w mixture of water and ethylene-glycol have been considered. Data confirm that pressure induces dissociation in both solvents, even if β-lactoglobulin shows an higher stability in 50% ethylene-glycol. An original global fitting procedure has been used to derive the thermodynamic parameters that describe the dissociation equilibrium. esult, the role of the solvent in protein dissociation has been observed to reflect on volume and compressibility changes.