Pressure and the water relations of proteins I—isoelectric gelatin gels

Abstract

Recent work on the structure of fibre proteins, as deduced form X-ray analysis, suggests that the bound water of hydration of proteins cannot be regarded as being simply a complete shell of water around the protein molecule or micelle. It seems much more probable that the water is localized around definite points and in a recent paper one of us has suggested two possible mechanisms of hydration. Katz, Svedberg, Rosenbaum§ and other have followed the thermal, vapour pressure and volume changes when a dried protein takes up water. Their work also suggests that the linkages or orientating forces holding water to the protein are not uniform in strength. More recent work on the freezing of gelatin gels which is discussed later in this paper has confirmed this and given figures for the amounts of water held by the gelatin at different activities of the water.