Wheat germ agglutinin is a 36,000 molecular weight protein consisting of two identical subunits. WGA contains a group of closely related isolectins, with an isoelectric point about pH 9. The receptor sugar for WGA is N-acetylglucosamine, with preferential binding to dimers and trimers of this sugar. WGA can bind oligosaccharides containing terminal N-acetylglucosamine or chitobiose, structures which are common to many serum and membrane glycoproteins. Bacterial cell wall peptidoglycans, chitin, cartilage glycosaminoglycans and glycolipids can also bind WGA. Native WGA has also been reported to interact with some glycoproteins via sialic acid residues (see succinylated WGA). This lectin has proven useful for the purification of insulin receptors and for neuronal tracing. This biotinylated lectin conjugate is prepared from affinity-purified lectin and is optimally labeled with biotin. Essentially free of inactive lectin conjugate and containing no free biotin, this biotinylated lectin provides an ideal intermediate for examining glycoconjugates using the Biotin-Avidin System. First the biotin-labeled lectin is added, followed by the VECTASTAIN® ABC Reagent, Avidin D conjugate, or streptavidin derivative. Another possible application is in the isolation of lymphokines and other products of mitogenic stimulation. |