GLYCOCONJUGATES .5. POLYMERIC SUGAR LIGANDS AVAILABLE FOR DETERMINING THE BINDING-SPECIFICITY OF LECTINS

Systematic syntheses of polymerizable N-acetyllactosamine and related disaccharide derivatives have been accomplished by introducing an n-pentenyl group at each reducing end as a simple and versatile polymerizable aglycon. Radical copolymerizations of these sugar monomers with acrylamide proceeded smoothly in water by means of ammonium persulfate and N,N,N',N'-tetramethylethylenediamine as initiators and to give water-soluble glycopolymers in good yields. In addition to chemical syntheses of glycopolymers, chemoenzymic galactosylation of the polymeric GlcNAc ligand was also completely performed by means of bovine galactosyl transferase activity in the presence of uridine 5'-diphosphogalactose as a sugar donor. These glycopolymers were demonstrated to exhibit enhanced binding capacity with lectins on the basis of polymeric sugar-cluster effect. It was suggested that the polymeric LacNAc ligand showed much higher affinity to Erythrina corallodendron lectin than other polymers having positional LacNAc isomers from the inhibitory assay of hemagglutination by Erythrina corallodendron. The order of the inhibitory effects of these polymers on hemagglutination by Erythrina corallodendron was Gal beta(1-4)GlcNAc (LacNAc) >> Gal beta(1-4)Glc (Lac) >> Gal beta(1-3)GlcNAc > Gal beta(1-6)GlcNAc similar or equal to Gal.