Figure 4.

Binding of the PQIQ peptide to NCS-1 monitored using tryptophan fluorescence. Changes in tryptophan fluorescence following sequential additions of the PQIQ peptide to the final indicated concentrations. Recombinant NCS-1 at a concentration of 1 μM in a buffer [50 mM Tris (pH 7.5), 50 mM NaCl, and 5 mM CaCl₂] was titrated with PQIQ at 50 μM to 1 mM under the same buffer conditions. The data were fit using a logistic equation and nonlinear curve fitting. Data are plotted as means ± SEM for three independent experiments.