A Spectrophotometric Study of the Carbohydrate Binding Site of Concanavalin A

The carbohydrate binding sites of the jack bean lectin, concanavalin A, were studied spectrophotometrically. A number of ligands were examined for their ability to displace the chromogenic ligand p-nitrophenyl α-d-mannopyranoside. It is shown that this technique provides a simple and convenient approach for obtaining association constants for a series of displacing ligands. The data can best be interpreted in terms of a single carbohydrate binding site per monomeric unit for the protein in solution.