Fig. 2. Calcium binding to S100A13 and the effect of zinc. Flow dialysis at 25°C in 50 mM Tris HCl, pH 7.5, 150 mM KCl, with (circles; two different experiments) or without 100 µM zinc (triangles). Protein concentration is 25 µM. The lines connecting the symbols were generated using the Adair equation for four sites with the constants (translated to stoichiometric constants as described in the Materials and Methods) indicated in Table 1.