The Dielectric Method of Estimating Protein Hydration

The dielectric method measuring protein hydration depends on the assumption of the existence of a frequency range where the water molecules bound to the protein molecule are incapable of turning in an applied electric field while the free water molecules can still rotate. Thus the difference between the dielectric constant of pure water and the dielectric constant of the protein solution at any frequency in this range gives a measure of the quantity of water tightly bound to unit weight of protein. The investigations were performed with human serum albumen and it is concluded that the hydration factor in the temperature range 25°c-37°c is about 0·4 grams of water per gram of serum albumen with an upper limit of 0·85. Methods of reducing errors and prospects of increasing the accuracy in future work are considered.