On the possibility of estimating weak interactions of macromolecules in solutions from the experimental viscous flow activation energies data

Abstract

The initial viscosity and activation energy in viscous flow of the systems: water(W)-casein(C)-polysaccharide(PS) (gum arabic(G),de-xtran(D), extran sulfat (DS)) have been determined for various ionic strengths corresponding to total or limited thermodynamic compatibility of macrocomponents. Excess activation energy ΔH η E due to the protein-polysaccharide interactions has been calculated. It is positive for systems with total compatibility and negative for systems with limited compatibility. Moreover, it yields information on type of the protein-polysaccharide interactions. Negative ΔH η E means that repulsive forces are dominant, while positive ΔH η E means that attractive forces are dominant. Since the properties of the systems W-C-D and W-C-DS are similar, it is believed that C-D complexes can possibly be formed with an energy ∼ 2 kT(10 mJ/g).