Jacalin lectin (AIA) is purified by affinity chromatography and is tetrameric two-chain structure consisting of four identical protomers with an isoelectric point of pH 7.8. The lectin has specificity for blood group types O (+SA) and T. Jacalin is considered a galactose-specific lectin and elutes with galactose or melibiose. A post-translational proteolytic modification of Jacalin gives the lectin a novel carbohydrate-binding site involving the N terminus of the α-chain. The protein’s structure explains it’s carbohydrate-binding specificity of T-antigen disaccharide Galβ1,3GalNAc. Potent inhibitors of jacalin include D-galactose, β-Met-Gal and 2-deoxy-α-D-galactose.