Thermodynamic incompatibility of proteins and polysaccharides in solutions

The thermodynamic incompatibility of proteins and polysaccharides is of a general nature. This phenomenon is observed under conditions which inhibit complexing between proteins and polysaccharides and promote association between macromolecules of the same type, i.e. provide self-association of biopolymers. Conditions for incompatibility are dependent on the structure and composition of a given biopolymer pair. Incompatibility decreases in the order: carboxyl-containing polysaccharides > neutral polysaccharides > sulphate-containing polysaccharides. Normally, linear polysaccharides are more incompatible with proteins than branched polysaccharides. The difference in hydrophilicity between proteins and polysaccharides, the so-called Δχ-effect, is of great importance for phase equilibria in protein—polysaccharide—water systems and significantly affects this phenomenon. This is reflected in the marked tie slope asymmetry of the phase diagrams of mixed pro tein—polysaccharide solutions.