Figure 3.

Fluorescence quenching in FeuA depends on the labeling position and the fluorophore. (A–D) Fluorescence trajectories (left) of single-fluorophore-labeled FeuA in the presence of 25 nM FeBB (A and C) or 40 nM (B and D) and corresponding histogram of the count rate ratios N_B⋅DD/N_F⋅DD or N_B⋅AA/N_F⋅AA of all molecules (right) are shown. In the fluorescence trajectories, donor (green) and acceptor (red) count rate with the most probable state trajectory of the HMM (black) are shown. In the histogram, bars are the data and solid line a Gaussian fit. A 95% confidence interval for the average of the brightness ratios is indicated. The number of analyzed molecules is provided in Table S3. To see this figure in color, go online.