Isolation and characterization of two N-acetyl-D-lactosamine specific lectins from tubers of Arisaema intermedium Blume and A. wallichianum Hook f.

Two new lectins were purified from the tubers of Arisaema intermedium Blume and A. wallichianum Hook. f. (family: Araceae) by affinity chromatography on asialofetuin-linked amino activated silica beads. The bound lectins were eluted with 0.1 M glycine-HCl, pH 2.5. They gave a single band corresponding to subunit M(r) 13.4 kDa in SDS-PAGE, pH 8.3. On gel filtration chromatography, the lectins showed a M(r) of 51.2 kDa, suggesting a homotetrameric structure. Both the lectins gave a single peak on size exclusion HPLC and cation-exchange columns and a single band on PAGE, pH 4.5. However, like other monocot lectins, they gave multiple bands in isoelectric focusing and at PAGE 8.3. The lectins were inhibited by N-acetyl-D-lactosamine (LacNAc), a disaccharide and asialofetuin, a complex desialylated serum glycoprotein. They had no requirement for divalent metal ions i.e., Ca2+ and Mn2+ for their activity and were found to be mitogenic towards human lymphocytes. A. intermedium showed antiproliferative effect against various human cancer cell lines in vitro.