Figure 5

Comparison of thermodynamic stability of modified and non-modified protein. A. GdmCl-induced equilibrium denaturation of the nuclease (squares) and its modified variant (circles) in 20 mM phosphate buffer pH 7.4 at 25°C. The protein concentration was 1 μM. The fit to a two-state model is shown and the parameters obtained are displayed in Table 1. B. Thermally-induced equilibrium denaturation of the nuclease (squares) and its modified variant (circles) in 20 mM phosphate buffer pH 7.4 in the presence of 2.5 M GdmCl. The protein concentration was 25 μM. The fit to a two-state model is shown and the free energy value obtained after extrapolation to standard conditions (25°C in the absence of GdmCl) is the same within error as that obtained by GdmCl denaturation (Table 1).