Figure 2.

The plot of log k_obs vs. pH for pH-induced unfolding/refolding in a citrate buffer (2 mM citrate/30 mM NaCl) at 4.5°C for WT (A) and the double mutant H24V/H119F (B). Both mutant and WT curves are fitted by using the same pK_a values (Table 1), with reference values k_u = 0.001 and k_f = 6 (A) or with k_u = 2 × 10⁻⁵ and k_f = 9 (B). The rate constants are given in units of s⁻¹ and the reference values refer to pH 9.