Lowering of the freezing temperature of water at the protein surface due to electric field

A new complementary mechanism of inhibiting water freezing at protein surface is proposed. It is based on the idea that the effect of the local electrostriction pressure Π related with the local electric field in the immediate vicinity of protein molecule on the properties of water is the same as that of the external pressure P. The compressing action of Π can let water attain a state within the region in the P-T phase diagram where it remains liquid below 0 °C. A model approach, recently developed to account for the enhanced density of water in double layers at protein molecules immersed in aqueous solutions, is followed. It is argued that, depending on the values of their surface charge densities, some local regions of surfaces of protein molecules prevent one or two monomolecular layers of the adjacent water from freezing by the effect of the electrostriction pressure.