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Lens culinaris agglutinin has a molecular weight of approximately 49,000 and is composed of four subunits - two of about 17,000 daltons and two of 8,000 daltons. The isoelectric point of LCA is approximately pH 8.5. LCA recognizes sequences containing a-linked mannose residues. Like other mannose specific lectins, divalent cations such as calcium and manganese are required for sugar binding activity.
By recognizing additional sugars as part of the receptor structure, LCA has a narrower specificity than Con A. For example, an a-linked fucose residue attached to the N-acetylchitobiose portion of the core oligosaccharide markedly enhances affinity. By exploiting this narrower specificity, glycoproteins and glycopeptides can be subfractionated with LCA after initial isolation with Con A.
LCA has been employed to separate lymphocyte populations, as a potent T-cell mitogen, and as one of the most effective agents in preventing skin allograft rejection in model systems. LCA is also used to purify numerous glycoproteins (including immunoglobulins, histocompatibility antigens, a2-macroglobulin, etc.) as well as to fractionate glycopeptides from a variety of glycoproteins. |