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

Systematic syntheses of polymerizable N-acetyllactosamine and related disaccharide derivatives have been accomplished by introducing an n-pe ntenyl group at each reducing end as a simple and versatile polymeriza ble aglycon. Radical copolymerizations of these sugar monomers with ac rylamide proceeded smoothly in water by means of ammonium persulfate a nd N,N,N',N'-tetramethylethylenediamine as initiators and to give wate r-soluble glycopolymers in good yields. In addition to chemical synthe ses of glycopolymers, chemoenzymic galactosylation of the polymeric Gl cNAc ligand was also completely performed by means of bovine galactosy l transferase activity in the presence of uridine 5'-diphosphogalactos e as a sugar donor. These glycopolymers were demonstrated to exhibit e nhanced binding capacity with lectins on the basis of polymeric sugar- cluster effect. It was suggested that the polymeric LacNAc ligand show ed 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 inhibi tory effects of these polymers on hemagglutination by Erythrina corall odendron 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.