Figure 1.

(a) Schematic of a divalent ligand–receptor system: The receptor has two binding pockets with a distance d from each other and a binding range σ. The ligand consists of two identical ligand units, connected via a spacer of contour length L. The end-to-end distance of the ligand is denoted as r. (b) Binding modes of a divalent ligand: (1) One ligand occupies one binding pocket. (2) Two ligands occupy two binding pockets. (3) One ligand occupies both binding pockets.