Figure 1.

Structural characterization of CcdB using various probes at pH 4 (cyan) and pH 7 (pink). (a) and (b) show far-UV and near-UV CD spectra of CcdB, respectively. (c) Fluorescence emission spectra of intrinsic tryptophan residues of CcdB obtained using an excitation wavelength of 295 nm are shown. (d) Stern-Volmer plot for native CcdB obtained at pH 4, pH 7, and unfolded CcdB (black). Fluorescence of CcdB in the absence of quencher, relative to the fluorescence obtained at various concentrations of acrylamide quencher, is plotted as a function of acrylamide concentration. The dashed line through the data in the respective color represents the fit to the data using Eq. 1. The error bars represent standard error from two or more independent experiments. To see this figure in color, go online.