Phaseolus limensis agglutinin (LBA) is isolated from lima bean seeds and purified by affinity chromatography. LBA is composed of 30,000 Da subunits, of which two are joined by a disulfide bond. Each subunit contains a cysteine residue which is required for both itâ€™s carbohydrate- and metal-ion-binding activities. It has a carbohydrate specificity of terminal GalNAcÎ±(1,3)Gal that elutes with N-acetylgalactosamine. LBA agglutinates blood group A erythrocytes.