Fig. 4.

Urea-induced denaturation of wild-type CspA (filled circles), Y42W (plus signs), S52W (open squares), and T68W (open triangles) expressed as the fraction unfolded. Denaturation was followed by fluorescence emission intensity at 350 nm (excitation at 280 nm). The protein concentration was 3.5 μM in 50 mM potassium phosphate, 100 mM KCl at pH 7.0, at 25°C.