Cross-linked guaran: a versatile immunosorbent for D-galactopyranosyl binding lectins.

Affinity chromatography has become the standard procedure for isolation of lectins [ I] . In its most general form, a ligand which binds to the lectin is linked covalently to a solid matrix. However, an insoluble or cross-linked polysaccharide for which the lectin exhibits affinity can also be used as the adsorbent. Notable examples of this approach include the isolation of concanavalin A using Sephadex G-50 (cross-linked dextran, [2,3] ) the isolation of the Ricinus communis lectins using agarose [4] and the isolation of wheat germ agglutinin on chitin [S] . The documented specificity of the lectins from the seeds of Bandeiraea simplicifolia [6] and Ricinus communis [7] for D-galactopyranosyl end units suggested that these as well as other lectins that bind these sugar units could be isolated on cross-linked guaran (guar gum). Guaran is a galactomannan composed of a chain of @-(l-+4)-linked D-mannopyranosyl residues having side stubs of single a-D-galactopyranosyl units linked CK-( 1+6) to approximately one half of the /3-D-mannosyl residues [8]. The present report describes the preparation and evaluation of this new adsorbent for lectin isolation.