A comparison of the carbohydrate binding properties of two Dolichos biflorus lectins

The carbohydrate binding properties of the Dolichos biflorus seed lectin and DB58, a vegetative tissue lectin from this plant, were compared using two types of solid phase assays. Both lectins bind to hog blood group A + H substance covalently coupled to Sepharose 4B and this binding can be inhibited with free blood group A + H substance. However, the binding of the seed lectin is inhibited by D-GalNAc whereas DB58 binding was not inhibited by any monosaccharide tested, thus suggesting that its carbohydrate combining site may be more extensive than that of the seed lectin. The activities of these two lectins also differ from one another in ability to recognize blood group A + H substance adsorbed on to plastic and in the effects of salt and urea on their carbohydrate binding activities. Neither lectin showed glycosidase activity with p-nitrophenyl alpha-D-GalNAc or p-nitrophenyl beta-D-GalNAc.