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. Author manuscript; available in PMC: 2013 Mar 28.
Published in final edited form as: J Am Chem Soc. 2012 Mar 13;134(12):5637–5646. doi: 10.1021/ja211788e

Figure 3.

Figure 3

Monitoring the association of bovine carbonic anhydrase (BCA) with 4-carboxybenzene sulfonamide (1) immobilized on PEGA beads. We levitated functionalized PEGA beads in cuvettes in the standard levitation buffer. (A) Adding BCA to the levitation media resulted in a change in levitation height (h) that depended on time, and on the concentration of protein. The figure shows the fit of the experimental plots to the estimates from the reaction-diffusion model. The reaction-diffusion model predicts that the time to reach equilibrium should be proportional to the protein concentration (equilibration is predicted be faster with higher protein concentrations). (B) We illustrate the effect of the ligand concentration within the bead on the rate of change in levitation height. The data confirm that the time to reach equilibrium is inversely proportional to the ligand concentration, as predicted by the reaction-diffusion model.