Con A recognizes α-linked mannose present as part of a “core oligosaccharide” in many serum and membrane glycoproteins.
Biotinylated Concanavalin A 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.
At neutral and alkaline pH, Con A exists as a tetramer of four identical subunits; below pH 5.6, Con A dissociates into active dimers of 52 kDa. Acetylation, succinylation, or other derivatizations can also produce stable forms with dimeric structures. (See succinylated Con A). Nicks in the sequence are often present in the purest preparations due to hydrolytic damage within the seeds.
Con A requires calcium or manganese ions at each of its four saccharide binding sites. Although these divalent metal ions are bound tightly to the polypeptide structure, buffers which can bind calcium (such as phosphate) generally should be avoided in diluting Con A, since a gradual loss in activity may occur.
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: mixture of 200 mM α-methylmannoside/200 mM α-methylglucoside