FIGURE 6.
Trends in chloride binding and activity for R522Q and R522K. Shown is a graphical representation of chloride binding and kinetic values obtained for C-domain (black bars), R522K (gray bars), and R522Q (white bars) with HHL, Z-FHL, and AngI as substrates. A, the Kd(app) values (mm) for chloride binding. *, AngI values were estimated from the report of Liu et al. (35). The kcat/Km value was taken as the percentage of the kcat/Km for the C-domain at 0 mm (B) and 20 mm (C) NaCl. D, change in thermodynamic parameters for R522Q and R522K. The ΔΔG, ΔΔH, and −TΔΔS values for C-domain, R522Q, and R522K with HHL, Z-FHL, and AngI are shown and represent the difference in ΔG, ΔH, and −TΔS between 0 and 20 mm NaCl.