Purification and properties of four monocot lectins from the family Araceae

Four new monocot lectins from the tubers of araceous plants, namely, Arisaema consanguineum Schott (ACA), A. curvatum Kunth (ACmA) and Sauromatum guttatum Schott (SGA) from the tribe Areae, and Gonatanthus pumilus D. Don (GPA) from the tribe Colocasieae have been purified by affinity chromatography on asialofetuin-linked amino activated silica beads. These lectins possess similar physicochemical and biological properties. All the lectins gave a single peak on HPLC size exclusion and cation exchange columns, and a single band on PAGE, (pH 4.5). In SDS-PAGE, all the lectins gave a single band corresponding to a subunit of M(r) 1,3000. All the lectins yielded multiple peaks on anion-exchange column, multiple bands on non-denatured PAGE (pH 8.3) and a family of bands on isoelectric focusing. The lectins agglutinate rabbit, rat and sheep red blood cells (RBCs) but are inactive towards human ABO erythrocytes. The haemagglutination activity of these lectins is inhibited by asialofetuin only, while simple sugars/derivatives including chitin, porcine mucin and fetuin did not react. In serological studies against rabbit anti-SGA serum, all four lectins produced immunoprecipitin lines. The lectins within each tribe were identical but the lectins belonging to the tribe Areae were only partially identical to the lectins from the tribe Colocasieae.