Affinity purified Phaseolus vulgaris lectin (PHA-E) is tetrameric glycoprotein and responsible for the erythroagglutinating properties of the PHA fraction. It has a carbohydrate specificity towards oligosaccharides and elutes with bovine thyroglobulin or acetic acid. PHA-E will bind to both human erythrocytes and lymphocytes, with a specificity towards blood group A (-SA). There are five times more PHA-E receptors on normal human lymphocytes than there are on erythrocytes. The crystal structure of a ligand-free PHA-E has a typical legume lectin fold characterized by two anti-parallel β-sheets and two short α-helices, and contains one GlcNAc residue of the N-linked glycan. Asparagine linked erythrocytes glycopeptide is an inhibitor of PHA-E induced agglutination and mitogenicity, and becomes inactive if treated with β-galactosidase. PHA-E binds di-galactosylated and bisected N-glycan. This lectin is widely used as a biochemical tool for detecting bisecting GlcNAc- and Gal-bearing glycoproteins.
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. Phaseolus vulgaris Lectin (PHA-E) is conjugated to HRP at an appropriate ratio to provide optimal staining characteristics.