Displacement chromatography of simple protein mixtures, using carboxymethyldextrans

Simple mixtures of proteins have been used as models to demonstrate that the fractionation of proteins by carboxymethyldextrans on an anion exchanger (Peterson, E.A. (1978) Anal. Biochem. 90, 767--784) is fundamentally a displacement process. Examples include the separation of two closely similar proteins, the A and B forms of beta-lactoglobulin. The use of carboxymethyldextran spacers was essential for good separation, since resolution based on protein--protein displacement was generally inadequate. The origins and effects of heterogeneity in the preparations used as spacers are discussed.