Glycotentacles: Synthesis of cyclic glycopeptides, toward a tailored blocker of influenza virus hemagglutinin

Blocking flu: A cyclic peptide, cyclo(Ser-Gly-Gly-Gln-Ser-His-Asp) 3, is an excellent scaffold for the synthesis of a cyclic glycopeptide carrying GM3 oligosaccharides with a potent inhibitory effect on the hemagglutination induced by the influenza virus. Tridentate binding of the gylcopeptide is shown to produce a much greater inhibitory effect than di- or monodentate binding. The shape of the glycopeptide protein scaffold, which is determined by the amino acid sequence employed, is also found to be significant in determining the inhibitory activity.