Microscopic description of protein thermostabilization mechanisms with disaccharides from Raman spectroscopy investigations

The mechanisms of protein thermostabilization by sugar were analysed for three disaccharides (maltose, sucrose and trehalose) characterized by the same chemical formula (C12H22O11). Raman scattering investigations simultaneously carried out in the low-frequency range and in the amide I band region provide a microscopic description of the process of protein thermal denaturation. From this detailed description, the influence of sugar on this process was analysed. The principal effect of sugars is to stabilize the tertiary structure, in which the biomolecule preserves its native conformation, through a strengthening of O-H interactions. This study shows that the bioprotective properties of sugars are mainly based on interactions between water and sugar. The exceptional properties of trehalose to preserve the native state of lysozyme by heating can be associated with its capability to distort the tetra-bonded hydrogen bond network of water.