Psophocarpus tetragonolobus lectin (PTL II, psophocarpin B1, a storage protein with chymotrypsin inhibitory activity), is isolated from winged bean seeds and purified by fractionation. The seed contains two lectins in which PTL II is the acidic of the two. This lectin agglutinates trypsinized and desialized erythrocytes of all three blood group types (A, B, and O). Nonpolar interactions play an important role in stabilization of the lectin-sugar complex. Projection of Î±1,3 linked Gal/GalNAc leads to steric hindrance and prevents the binding of blood group A and B reactive sugars.The unique specificity of PTL II makes it to be useful in isolation and characterization of terminally monofucosylated H-reactive oligosaccharides from those that are difucosylated or internally fucosylated.Biotin is a small molecule involved in a wide range of metabolic processes. This ligand forms a complex with Avidin and Streptavidin, resulting in the strongest non-covalent protein-ligand interaction known. Biotinylated Psophocarpus tetragonolobus Lectin (PTL/PTA II) has an appropriate amount of biotin bound to provide optimum detection characteristics when using an Avidin-HRP or Streptavidin-HRP conjugate. Biotinylated lectins allow for more sensitive detection in ELISA and Western-blotting applications.