Controlling Ligand Spacing on Surface: Polyproline-Based Fluorous Microarray as a Tool in Spatial Specificity Analysis and Inhibitor Development for Carbohydrate-Protein Interactions.

Multivalent carbohydrate-protein interactions are essential for many biological processes. Convenient characterization for multivalent binding property of proteins will aid the development of molecules to manipulate these processes. We exploited the polyproline helix II (PPII) structure as molecular scaffolds to adjust the distances between glycan ligand attachment sites at 9, 18, and 27 Å on a peptide scaffold. Optimized fluorous groups were also introduced to the peptide scaffold for immobilization to the microarray surface through fluorous interaction to control the orientation of the helical scaffolds. Using lectin LecA and antibody 2G12 as model proteins, the binding preference to the 27 Å glycopeptide scaffold, matched the distance of 26 Å between its two galactose binding sites on LecA and 31 Å spacing between oligomannose binding sites on 2G12, respectively. We further demonstrate this microarray system can aid the development of inhibitors by transforming the selected surface-bound scaffold into multivalent ligands in solution. This strategy can be extended to analyze proteins that lacking structural information to speed up the design of potent and selective multivalent ligands.