Thermal motions quantification of lysozyme in aqueous mixtures with different co-solvent: glycerol [C3H5(OH)3], trehalose [C12H22O11], sucrose [C12H22O11], and a chaotropic agent [CO(NH2)2] by osiris near-backscattering crystal analyser spectrometer

Thermal neutron scattering is a powerful tool to directly probe protein internal motions. Here, we report an incoherent neutron scattering study of the effect of glycerol-, disaccharide- CO(NH 2 ) 2 -aqueous mixtures on the internal dynamics of lysozyme powder. Mean-square displacement of amplitude motions as a function of temperature was evaluated. We showed the complex interdependence between the motions of the protein, water of hydration, and co-solvent. Analysis of data gives access to the geometry of the observed motions. Then the crucial role of the solvent mobility to activate thermal fluctuations is proposed.