Figure 2. Cu(II) binding to the E2 domain of APP measured by ITC.

We measured binding of Cu(II) to the E2 domain in non-coordinating buffer using isothermal titration calorimetry (ITC). Concentration of E2 domain in the cell was 26.5 µM and that of Cu(II) in the syringe was 1.27 mM. Measurements were performed at 25°C in 100 mM Mops 150 mM NaCl, pH 7.0. A model with two independent binding sites was required to obtain a fit to the data of integrated heat of binding. *The stoichiometry of the second binding event could not be determined with statistical significance. The data represent the average of two experiments ± standard deviation.