(A) The dependence of the kinetic rate constant of association, kon, on the concentration of less-penetrating PEGs; (B) The dependence of the kinetic rate constant of dissociation, koff, on the concentration of less-penetrating PEGs; (C) Free energy, ΔG, of the Syn B2-αHL complex formation in the presence of PEG-2k (black squares), PEG-4k (red circles) and PEG-8k (blue triangles). PEGs were symmetrically added to both sides of the chamber. The other experimental conditions were the same as those stated in the caption of Fig. 2.