Water effects on trehalose matrices studied through Molecular Dynamics

Saccharides, and in particular trehalose, are known for their high efficiency in protecting biostructures against adverse environmental conditions [1], although the preservation mechanism is still debated. Experiments and simulations on carboxy-myoglobin (MbCO) have shown that the protein dynamics is highly inhibited in a low-water trehalose host medium, the inhibition being markedly dependent on the amount of residual water. Trehalose effects have been related to its hydrogen-bonding (HB) properties, which have been studied by Infrared Spectroscopy (FTIR) and Molecular Dynamics simulations (MD) [2,3,4]. FTIR, through the study of the water association band and of the CO stretching band, pointed out the existence of a reciprocal protein-matrix coupling modulated by water content. In these systems different classes of water molecules could be distinguished, whose ratio is altered by chaotropic and kosmotropic solutes [3,5]. MD simulations pointed out that water molecules shared between protein and sugar could modulate the strength of the constraints imposed by the surrounding matrix on the protein, thus affecting its internal dynamics (atomic fluctuactions on ps/ns time scale) [4]. A deeper understanding of the role of water molecules in the dynamics of these system could shed light on trehalose peculiarity.