Con A recognizes α-linked mannose present as part of a “core oligosaccharide” in many serum and membrane glycoproteins. 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.