Figure 3.

Urea denaturation. Equivalent amounts of wild-type N-62 StAR were equilibrated overnight with different concentrations of urea buffered with 10 mM Tris or 20 mM Na₂HPO₄ at pH values ranging from 2.0 to 8.3. The ellipticity at 222 nm was recorded in a 1-mm path-length cuvette at 20°C and plotted against the urea concentration, as determined in a refractometer. For clarity only data obtained at pH 4.5 (●), 4.0 (■), and 3.0 (▴) are presented.