Figure 4.
Determination of the affinity constant of GbpAHp for three different glutathione forms: the oxidized (GSSG), the reduced (GSH), and an S-derivatized form (S-me-GSH). Isothermal titration data for the titration of GbpAHp with either GSSG, GSH, or S-me-GSH in 10 mMTris-HCl, pH 7.4. The upper panels show the calorimetric titrations for 10-μl injections with 300 s between injections. The lower panels represent the integrated heat values (from the upper panels) as a function of the protein/ligand molar ratio in the cell. The solid line represents the best fit of the single-site model to the experimental points.