FIGURE 4.
Ionic strength dependence of NBD-ZPI and NBD-cZPI interactions with PZ. The graph shows a Debye-Hückel analysis of the dependence of the binding free energy (−ΔG0bind) of NBD-labeled intact ZPI (●) and NBD-labeled cZPI (○) interactions with PZ on the square root of the ionic strength. −ΔG0bind was measured from equilibrium binding titrations of the interactions as a function of ionic strength as in Fig. 2. Solid lines are fits by Equation 2 under “Experimental Procedures.” Error bars represent ±S.E.