Unlike mixtures of synthetic polymers mixtures of polysaccharides and
protein-polysaccharide mixtures the thermodynamic incompatibility of p
roteins in solution is notable for the following general features. Thi
s phenomenon is typical of mixtures of proteins belonging to different
classes according to the Osborne classification. A relatively high ph
ase separation threshold is the other characteristic feature of mixed
protein solutions. Factors such as pH, ionic strength and temperature
only slightly affect protein incompatibility. This is probably due to
the compactness and rigidity of protein molecules. Accordingly incompa
tibility is strongly dependent upon the conformational state of the pr
oteins and is enhanced by protein denaturation.