Thermodynamic parameters for the binding of Ras proteins to Ca2+/CaM as determined by ITC (A) and dansyl-CaM fluorescence titration (B) at 25.0°C.

The value of n was also determined as 1.0 for the binding of K-RasB to Ca2+/CaM by using Cross-linking.NB, no binding observed in the present conditions.Thermodynamic parameters, Kd, , and n, were determined using a single set of identical sites model. The standard molar binding free energy () and the standard molar binding entropy () for the binding reaction were calculated using Equations 1 and 2 respectively. The buffer used was 20 mM HEPES buffer (pH 7.4) containing 150 mM NaCl, 1 mM CaCl2, and 1 mM MgCl2. Errors shown are standard errors of the mean.