Protein hydration and the huge electrostriction.

Recent experiments indicated the existence of hydration shells about biomolecules with densities markedly higher than that of bulk water. The compression is due to the pull of the dipoles of H(2)O molecules, necessary to achieve the thermodynamic equilibrium, from bulk water into the high field (approx. 10(9) V/m) region at the surface of the protein molecule. The electric field values at the surfaces of the biomolecules are calculated on the basis of the known densities. The reverse calculation of the limiting density values on the basis of known electric field distributions is performed, too. The results compare favourably with experiment.