Glycopeptide dendrimers: Tuning carbohydrate-lectin interactions with amino acids
Glycodendrimers, such as glycoclusters and glycopolymers, are known to be very useful molecules to probe carbohydrate-lectin interactions. Herein, new second generation glycopeptide dendrimers (G2a-f) presenting a L-lysin-based (Lys) tetraantennary scaffold, four external thiomannosyl residues and, in the case of compounds G2b-f, four copies of a variable amino acid (X1) were synthesized and used as Concanavalin A (Con A) inhibitors. An increased-sensitivity Enzyme-Linked Lectin Assay (ELLA) was also developped to evaluate precisely the relative strength of the glycodendrimer-lectin interactions. Glycopeptide dendrimer G2e, for which L-tyrosin (Tyr) was used as a variable amino acid, led to optimal inhibition properties. Additionally, glycopeptide dendrimers G2g-k built on a scaffold displaying four external Tyr and more internally, four copies of a variable amino acid (X2) were synthesized and involved in the mentioned ELLA. Even if no strong improvement was observed, such structural modulations could also modify the inhibition properties of glycopeptide dendrimers. Finally, mono-, di- and octavalent analogs of G2e, noticed respectively G0, G1 and G3, were produced and assaied. Multivalency then appeared as a key feature since inhibition properties of these glycoconjuguates increased with the number of carbohydrate moieties and a relatively strong cluster effect was obtained for the octavalent derivative.