作者:Nathalie Berthet、Baptiste Thomas、Isabelle Bossu、Emilie Dufour、Emilie Gillon、Julian Garcia、Nicolas Spinelli、Anne Imberty、Pascal Dumy、Olivier Renaudet
DOI:10.1021/bc400239m
日期:2013.9.18
Following an iterative oxime ligation procedure, cyclopeptide (R) and lysine-based dendron (D) were combined in all possible arrangements and successively functionalized with alpha-fucose and beta-fucose to provide a new series of hexadecavalent glycosylated scaffolds (i.e., scaffolds RD16, RR16, DR16 and DD16). These compounds and smaller analogs (tetra- and hexavalent scaffolds R-4 and R-6) were used to evaluate the influence of the ligand valency and architecture, and of the anomer configuration in the binding to the alpha Fuc-specific lectin LecB from Pseudomonas aeruginosa. Competitive enzyme-linked lectin assays (ELLA) revealed that only the RD16 architecture displaying alpha Fuc (9A) reaches strong binding improvement (IC50 of 0.6 nM) over alpha MeFuc, and increases the alpha-selectivity of LecB. Dissociation constant of 28 nM was measured by isothermal titration micorcalorimetry (ITC) for 9A, which represents the highest affinity ligand ever reported for LecB. ITC and molecular modeling suggested that the high affinity observed might be due to an aggregative chelate binding involving four sugar head groups and two lectins. Interestingly, unprecedented binding effects were observed with beta-fucosylated conjugates, albeit being less active than the corresponding ligands of the alpha Fuc series. In particular, the more flexible lysine-based dendritic structures (15B and 18B) showed a slight inhibitory enhancement in comparison with those having cyclopeptide core.