SYNTHESIS OF ARTIFICIAL N-GLYCOPOLYPEPTIDES CARRYING N-ACETYLLACTOSAMINE AND RELATED-COMPOUNDS AND THEIR SPECIFIC INTERACTIONS WITH LECTINS

Artificial N-glycopolypeptides carrying N-acetyllactosamine (LacNAc) o r related compounds were synthesized. First, sugars were converted int o their corresponding beta-glycosylamines with ammonium hydrogen carbo nate. Then, the beta-glycosylamines were condensated with the carboxyl groups of poly(L-glutamic acid). N-Glycopolypeptides with different d egrees of substitution of sugars were isolated by passage through a co lumn of Sephadex G-25. These synthetic polymers were used as model com pounds in the analysis of oligosaccharide-lectin interactions. Interac tions with some lectins were investigated by agar-gel double-diffusion tests and in terms of inhibition of hemagglutination. A glycopolypept ide substituted with LacNAc reacted with Erythrina cristagalli aggluti nin (ECA), peanut (Arachis hypogaea) agglutinin (PNA), Ricinus communi s agglutinin-120 (RCA(120)), wheat germ (Triticum vulgaris) agglutinin (WGA) lectins, which recognize either galactosyl or N-acetylglucosami ne (GlcNAc) residues. Other synthetic glycopolymers carrying N-acetyli solactosamine, GlcNAc, N,N'-diacetylchitobiose, or N,N',N ''-triacetyl chitotriose also reacted with WGA, and these last two polymers inhibit ed hemagglutination most. Of these five glycopolypeptides, only the on e substituted with LacNAc reacted with EGA. These sugar-substituted gl ycopolypeptides interacted specifically with the corresponding lectins , no matter how much shorter the sugar side chains of the glycopolymer s were than those of natural glycoproteins.