Figure 1.

Calorimetric titration of the R21A mutant of Spc-SH3 with the p41 peptide. A. Experimental ITC thermograms obtained at pH 7.0 and 25°C by consecutive injections of variable volumes (ranging between 1.3 and 16 μl) of a p41 solution into the Spc-SH3 R21A mutant solution (1) and the buffer solution (2), respectively. B. Binding isotherms obtained at pH 7.0 using three different buffers (phosphate, squares; hepes, circles; and imidazole, triangles). Symbols represent the experimental data for the corrected and normalized heats produced by the binding after each injection. The continuous lines correspond to the best global fitting of the three isotherms using equation 1 (see Material and Methods).