Biological Activity
Concanavalin A interacts with diverse receptors containing mannose carbohydrates, notably rhodopsin, blood group markers, insulin-receptor the Immunoglobulins and the carcino-embryonary antigen (CEA). It also interacts with lipoproteins.
ConA agglutinates strongly erythrocytes irrespective of blood-groups, and various cancerous cells. It was demonstrated that transformed cells and trypsin-treated normal cells do not agglutinate at 4°C, thereby initiate suggesting that there is a temperature-sensitive step involved in ConA-mediated agglutination.
ConA-mediated agglutination of other cell types has been reported, including muscle cells (myocytes), B-lymphocytes (through surface Immunoglobulins), fibroblasts, rat thymocytes, human fetal (but not adult) intestinal epithelial cells, and adipocytes. ConA is also a lymphocyte mitogen.
ConA interacts with the surface mannose residues of many microbes, like the bacteria E. coli, and Bacillus subtilis and the protist Dictyostelium discoideum.
It has also been shown as a stimulator of several matrix metalloproteinases (MMPs).
ConA has proven useful in applications requiring solid-phase immobilization of glycoenzymes, especially those have proved difficult to immobilize by the traditional covalent coupling. Using ConA-couple matrices, such enzymes may be immobilized in high quantities without a concurrent loss of activity and/or stability. Such noncovalent ConA-glycoenzyme couplings may be relatively easily reversed by competition with sugars or at acidic pH. If necessary for certain applications, these couplings can be converted to covalent bindings by chemical manipulation.
A recent (2009) report from Taiwan demonstrated potent therapeutic effect of ConA against experimental hepatoma (liver cancer); in the study by Lei and Chang, ConA was found to be sequestered more by hepatic tumor cells, in preference to surrounding normal hepatocytes. Internalization of ConA occurs preferentially to the mitochondria after binding to cell membrane glycoproteins, which triggers an autophagic cell death. ConA was found to partially inhibit tumor nodule growth independent of its lymphocyte activation; the eradication of the tumor in the murine in situ hepatoma model in this study was additionally attributed to the mitogenic/lymphoproliferative action of ConA that may have activated a CD8+ T-cell-mediated, as well as NK- and NK-T cell-mediated, immune response in the liver.
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