Enzymatic glycosylation of triazole-linked GlcNAc/Glc-peptides: synthesis, stability and anti-HIV activity of triazole-linked HIV-1 gp41 glycopeptide C34 analogues.

Long-lasting sweet proteins: The chemoenzymatic synthesis of a triazole (T)-linked glycosylated C34 fragment from HIV-1 gp41 is described. The glycopeptide shows high solubility, excellent fusion inhibition, and as shown in the graph, promising protease resistance. Endoglycosidase-catalyzed transglycosylation of triazole-linked glucose (Glc) and N-acetylglucosamine (GlcNAc)-containing dipeptides and polypeptides was achieved by using synthetic sugar oxazoline as the donor substrate. It was found that both N- and C-linked Glc/GlcNAc-containing triazole derivatives were effective substrates for endo-beta-N-acetylglucosaminidase from Arthrobacter (Endo-A) for transglycosylation; this demonstrates a broad acceptor substrate specificity for Endo-A. This chemoenzymatic method was successfully used for the synthesis of a novel triazole-linked C34 glycopeptide derived from the HIV-1 envelope glycoprotein, gp41. We found that the synthetic C34 glycopeptide possesses potent anti-HIV activity with an IC(50) of 21 nM. The triazole-linked C34 glycopeptide demonstrated a much enhanced stability against protease- and glycoamidase-catalyzed digestion; this shows the protective effects of glycosylation and the stability of the triazole linkage. These favorable properties suggest that the triazole-linked C34 glycopeptide might be valuable for further development as an anti-HIV drug candidate.