A
lectin with in-vitro anticancer activity against established human
cancer cell lines has been purified by affinity chromatography on
asialofetuin-linked amino activated
silica beads from the tubers of Arisaema tortuosum, popularly known as Himalayan Cobra lily, a monocot plant from the family Araceae. The bound Arisaema tortuosum
lectin (ATL) was eluted with
glycine-HCl
buffer, pH 2.5. ATL was effectively inhibited by
asialofetuin, a complex desialylated serum
glycoprotein as well as by N-acetyl-D-
lactosamine, a
disaccharide. It gave a single band corresponding to a subunit molecular weight of 13.5 kDa in SDS-PAGE, pH 8.8 both under reducing and non-reducing conditions. When subjected to gel-filtration on Biogel P-200, it was found to have a molecular weight of 54 kDa, suggesting a homotetramer structure, in which individual
polypeptides are not bound to each other with
disulfide bonds. ATL is a
glycoprotein with 0.9 %
carbohydrate content, stable up to 55(o)C and at pH 2 to 10. The
lectin had no requirement for divalent
metal ions i.e. Ca(2+) and Mn(2+) for its activity. However, as reported for other monocot
lectins, ATL gave multiple bands in isoelectric focusing and Native PAGE, pH 8.3. The
lectin was found to inhibit in vitro proliferation of human
cancer cell lines HT29, SiHa and OVCAR-5.