Oligosaccharide Specificity of the Fucolectin from the Bark of Laburnum (Laburnum anagyroides)

A comparative study of fine carbohydrate specificity of the lectin from the bark of laburnum Laburnum anagyroides (LABA) and the fucolectin from asparagus pea Tetragonolobus purpureus (TPA) was performed using inhibition of agglutination of the complex formed by H-active neoglycoprotein and nanoparticles of colloidal gold. Both lectins bound most strongly the H type 2 oligosaccharides comprising O-glycans; however, LABA was almost unable to discriminate between them. LABA bound more weakly the H type 6 trisaccharide (Fuc1-2Gal1-4Glc) and difucosyllactose (Fuc1-2Gal1-4[Fuc1-3]Glc), a glucoanalogue of the Le^y antigen, and, even more weakly, the Le^a pentasaccharide lacto-N-fucopentaose II (Gall-3[Fucl-4]GlcNAcl-3Gall-4Glc). However, LABA did not bind the antigens Le^b, Le^c, and Le^d, very poorly interacted with the terminal Le^x, and somewhat more strongly bound the internal Le^x. The lectin also had a hydrophobic binding site. Both lectins exhibited a cluster effect with polymeric ligands (neoglycoproteins).