Fig 2. Equilibrium fluorescence titration of TChz binding to TBZ_Y139W.

Experiments were performed by titrate 20 μL 30 μM TChz into 800 μL 5 μM TBZ_Y139W in 0.01 M PBS (pH 7.4), at 298 K. The artificial fluorescence changed caused by decrease of TBZ_Y139W concentration was corrected by subtracting baseline of blank titration control experiment. Data of titration of TChz into TBZ_Y139W in varies NaCl concentration (A) and titration of TChz into TBZ_Y139W in varies urea concentration (B) are plotted with the best fitting to an equilibrium two-state model as described in the supporting information.