Vicia Villosa Lectin (VVL, VVA), Agarose bound

This lectin is a family of tetrameric glycoproteins consisting of combinations of A and B subunits similar in structure to PHA and GSL I. The dominant isolectins in our preparations appear to be B subunit-rich. VVL recognizes preferentially ?- or ?-linked terminal N-acetylgalactosamine, especially a single ?-N-acetylgalactosamine residue linked to serine or threonine in a polypeptide (the Tn antigen). Evidence suggests that this lectin also may require specific amino acid sequences at the receptor site of glycosylation. The disaccharide galactosyl (?-1,3) N-acetylgalactosamine is also a potent inhibitor of this lectin.

Agarose bound* Vicia villosa lectin is prepared using our affinity-purified lectins. Heat stable, cross-linked 4% agarose beads with a molecular weight exclusion limit of about 2x10⁷ daltons are used as the solid-phase matrix to which the lectins are covalently coupled. The attachment of the lectins to the beads is carefully controlled to preserve lectin activity and minimize conformational changes of the bound lectins that might result in nonspecific ionic or hydrophobic interactions. The technique we have developed to couple lectins to agarose beads inserts a hydrophilic spacer arm between the lectin and the matrix.

This coupling method provides several advantages over the traditional cyanogen bromide procedure:

• Maximum carbohydrate binding activity of the coupled lectins is retained
• Linkage is stable over a range of pH values
• Conjugated proteins are not leached off the beads by Tris or other routinely used buffers
• No residual charges are present after conjugation. This minimizes non-specific binding to the matrix.

Our agarose bound lectins are supplied at a constant concentration of lectin per ml of settled beads. The concentration for each lectin is selected to achieve the highest glycoconjugate binding capacity per mg of lectin present in the beads. Each lot is tested for its binding capacity using glycoproteins known to bind the lectin. This provides a guideline for the user and assures the quality of our agarose bound lectins.

Inhibiting/Eluting Sugar: 200 mM N-acetylgalactosamine

*3 mg lectin/ml gel