Efficient synthesis of spacer-N-linked double-headed glycosides carrying N-acetylglucosamine and N,N′-diacetylchitobiose and their cross-linking activities with wheat germ agglutinin

We describe here an efficient synthetic route to spacer-N-linked double-headed glycosides via a simple two-step procedure. N-Acetylglucosamine (GlcNAc) and N,N′-diacetylchitobiose [(GlcNAc)2] were treated with ammonia and the resulting N-β-glycosylamines were coupled to a series of dicarboxylic acids. Condensation with each dicarboxylic acid proceeded stereoselectively to give the corresponding β-N-linked double-headed glycoside without the need for any protection/deprotection steps. Interaction of the resulting N-linked double-headed glycosides with wheat germ agglutinin (WGA) were then investigated using a precipitation assay and an optical biosensor based on surface plasmon resonance (SPR). Spacer-N-linked double-headed glycosides bearing GlcNAc and (GlcNAc)2 were found to be capable of binding and precipitating WGA as divalent ligands. However, the length of the spacer groups between the two terminal sugar residues was found to greatly influence the cross-linking activities with the lectin.

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