[Relation between ovalbumin hydration and the nature of cations, their concentration and temperature]

The influence of temperature, nature and concentration and alkali metal chlorides on the hydration degree of ovalbumin (W) was studied by the method of proton magnetic relaxation. It is shown that W of ovalbumin at low temperatures is conditioned by the sum of W by strong and weak water binding sites of the protein molecule. The standard binding enthalpy of water by weak sites is independent of the nature and concentration of the low-molecular weight salt and comprises about 40 KJ mol-1. The addition of such salts to the protein solution leads to changes of W conditioned by the changes of the strong site hydration. The liotropic effect of Li+ and Cs+ on the protein solution is complicated by their interactions with the peptide groups of protein.