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.
Biotinylated WGA has an appropriate number of biotins bound to provide the optimum staining characteristics for this lectin. This conjugate is supplied essentially free of unconjugated biotins and is preserved with sodium azide.
I recently purchased a biotinylated lectin. The datasheet supplied with the lectin suggests including 0.1 mM Ca++as part of the recommended buffer to prepare a working solution. What should I specifically add, and why is this required?
From our experience we have found that some lectins require Ca++ to be present for optimal binding activity. We suggest using calcium chloride (CaCl2) to fortify working solutions and ensure a minimum level of Ca++ is meet. This may be particularly pertinent if using phosphate based buffers as diluents and storage solutions.
Wheat germ agglutinin (WGA) contains a group of closely related isolectins, with an isoelectric point about pH 9. This lectin is used for the purification of insulin receptors and for neuronal tracing. Native WGA has also been reported to interact with some glycoproteins via sialic acid residues (see succinylated WGA).
This biotinylated lectin is an ideal intermediate for examining glycoconjugates using the Biotin-Avidin/Streptavidin System. First the biotinylated lectin is added, followed by the VECTASTAIN ABC Reagent, Avidin D conjugate, or streptavidin derivative.
Inhibiting/Eluting Sugar: Chitin Hydrolysate or 500 mM N-acetylglucosamine with salt and/or acid elution generally required