The effect of various coupling methods on the adsorption of serum proteins by immobilized concanavalin A

Concanavalin A was coupled to Sepharose 6B after activation by cyanogen bromide, divinyl sulfone, or glutaraldehyde and its adsorption behavior toward human serum proteins was investigated. The capacity and selectivity of the lectin were influenced markedly by the method used for its immobilization. When coupled to agarose via CNBr, the resulting absorbent showed the highest capacity and the lowest selectivity relative to the other two derivatives. When coupled to agarose via divinyl sulfone, the lectin exhibited high selectivity but its adsorption capacity was significantly reduced. Coupling to agarose via glutaraldehyde gave an absorbent that behaved, in some respects, differently from the other two. The variability in the adsorption behavior of the immobilized concanavalin A is attributed in part to variations in the degree of multipoint attachment of the lectin or its subunits to the agarose matrix. The selectivity increases also with increasing sample load, irrespective of the coupling method used, apparently due to protein-protein displacement.