Figure 5.

HX isotherms of amide protons belonging to residues in helices. The GdmCl concentration-dependence of the free energy of opening to HX is shown for each of the amide protons from the helices that were used as probes. The solid line in each panel represents the free energy of global unfolding of Trx, as a function of GdmCl concentration, which was obtained from the equilibrium unfolding data of Figure 2 ▶. The dashed line shows the global unfolding free energy at each indicated GdmCl concentration, after correction for proline isomerization (see text). The solid lines through the data points are fits to Equation 8. All fits, except those for Ile 41 and Leu 42, were constrained to the value of m that was obtained for global unfolding (Fig. 2 ▶).