Fig. 3.

Folding and unfolding of OmpLA remain irreversible at a broad range of pH, however, hysteresis is lessened at acidic pH, especially at pH 3.8. The guanidine HCl concentrations of the midpoints of folding (●) and unfolding (○) titrations are plotted for titrations at various pH levels that were otheriwse prepared according to the scheme shown in Fig. 2A with incubation at 37° C for 40 hours. The excitation wavelength for all fluorescence samples was 295 nm.