Affinity chromatography of galactose containing biopolymers using covalently coupled Ricinus communis lectin to Sepharose 4B

Abstract

A galactose-specific lectin isolated from Ricinus communis beans has been covalently coupled to Sepharose 4B activated with cyanogen bromide. The immobilized lectin retains its polysaccharide-binding property. The Sepharose-lectin can be used for the purification of polysaccharides containing terminal nonreducing galactose. Only a small fraction of 'native fetuin' and 'native ceruloplasmin' are retarded on Sepharose-lectin. On analysis it was observed that they had a lower content of sialic acids as compared to the native and unbound glycoproteins (sialated fractions). However, on desialation, fetuin and ceruloplasmin were completely adsorbed to Sepharose-lectin. The asialoglycoproteins interact strongly with Sepharose-lectin as compared to 'partially sialated glycoproteins'. This has been attributed to the exposure of galactose residues of these glycoproteins on enzymatic desialation. These experiments demonstrated that Sepharose-lectin interacts with glycoproteins through their terminal, non-reducing galactose. On the basis of these experiments it is suggested that Sepharose-lectin can be used as an analytical tool for separation of 'fully sialated glycoproteins' from the 'partially sialated glycoproteins'.