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 α1,3 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.
Horseradish peroxidase (HRP) is a 40 kDa protein that catalyzes the oxidation of substrates by hydrogen peroxide, resulting in a colored or fluorescent product or release of light as a byproduct of the reaction. It is most commonly used for blotting, immunoassays and immunohistochemistry methods. Psophocarpus tetragonolobus Lectin (PTL/PTA II) is conjugated to HRP at an appropriate ratio to provide optimal staining characteristics.