Xenbase Image ID: 121654

Figure 6. (A) Energetics of CFTR relative binding selectivity. The filled circles are the relative well depth [|Δ(ΔG)well|, C(CN)3 reference] calculated using the ratio of the apparent inhibition constants (Table ) plotted as function of reciprocal anion radius, 1/r (Table ). The dashed line is the best fit to the data points. The solid line is the relative hydration energy [|Δ(ΔG)hyd|, C(CN)3 reference] calculated using plotted vs. 1/r for reference. Due to the fact that the measurements were made with respect to Cl (see materials and methods), it is not possible to calculate a value for Cl; however, the plot permits an extrapolation for Cl based on the size of the anion (highlighted with an arrow). (B) Anion-channel stabilization energies at the binding site plotted with respect to a vacuum reference phase. The filled circles are the well depths set by fixing the well depth for SCN at 12.5 kJ/mol (5.1 RT, based on the dissociation constant of 6.4 mM reported by Tabcharani et al. 1993) and adding the hydration energy plotted as function of reciprocal anion radius, 1/r. The dashed line is the best fit to the data points. The Cl point (○) shown is the well depth of 8.2 kJ/mol, based on the reported dissociation constant for Cl of 38 mM reported by Tabcharani et al. 1997, shown for comparison. The solid line is the hydration energy, |ΔGhyd|, calculated using plotted vs. 1/r. The dotted line is the solvation energy, |ΔGsolv|, calculated for a homogenous medium with a dielectric constant of 19 using plotted vs. 1/r, as in Fig. 4. Note that values of transfer energy greater than the hydration energy reflect energetic wells, whereas values less than the hydration energy reflect energetic barriers. Image published in: Smith SS et al. (1999) © 1999 The Rockefeller University Press. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View

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