Temperature dependence of protein dynamics as affected by sugars:: a neutron scattering study

Neutron scattering data on lysozyme-trehalose and lysozyme-sucrose aqueous mixtures, and on trehalose and sucrose aqueous mixtures are presented for a wide temperature range. Although the degree of protein coupling to solvent seems to be an open question in the literature, we present evidence that seems to be a firm link between a local dynamics of the protein with that of the glassy host. One of the objectives of this study was to explore the relationship between protein dynamics and glassy host. Measuring the < u (2)> of lysozyme mixtures, we arrive at a qualitative description of how their thermal stability is affected by the presence of two sugars at different temperatures. Whereas the Q dependence of the elastic incoherent structure factor gives information about the geometry and the amplitudes of the motions.