I. The role of carboxyl groups in the binding of specific carbohydrates to concanavalin A, the phytohemagglutinin of the jack bean, has been studied using two techniques: (I) H + titration in the presence and absence of methyl a-D-mannopyranoside, a specifically bound carbohydrate ligand and (2) chemical modification of the protein carboxyl groups employing glycine methyl ester and a water-solu...