Thermodynamic compatibility of proteins in aqueous media. Part 2. The effect of some physicochemical factors on thermodynamic compatibility of casein and soybean globulin fraction.

A study has been made on the effect of temperature, sodium chloride, pH and cysteine on the thermodynamic compatibility of casein and soybean globulin fraction in aqueous medium. The section of miscibility gap characterizing the influence of the indicated factors on the compatibility of proteins has been determined. Assessment has been made of the influence of pH and cysteine on a) the effective molecular weights of casein and soybean globulin fraction and b) the difference in the intensity of interaction between each protein and a solvent. The experimental data obtained on the compatibility of proteins were found in good agreement with the theoretical concepts which establish the dependence of the compatibility of polymers on the ratio of their molecular weights, the intensity of interactions between polymers, as well as on the difference in the intensities of interaction between each of them and a solvent, i.e. on the difference of protein hydrophilicities.