Figure 5
1H-15N HSQC spectra for the titration of CaM with the MBP peptide. A. Overlay of 1H-15N HSQC spectra of Ca2+/CaM alone (black) and the Ca2+/CaM-MBP peptide complex (pink; 1:0.333, blue; 1:0.666, red; 1:1). The samples contained 0.5 mM CaM, 120 mM NaCl, 2.5 mM CaCl2, and 50 mM deuterated Tris-HCl (pH 7.5) in 90% H2O and 10% D2O. Changes in cross-peak positions were quantified by [(Δ15NHz)2 + (Δ1HHz)2]1/2, and some cross-peaks showing larger shifts are indicated on the figure. B. Chemical shift perturbations quantified by [(Δ15NHz)2 + (Δ1HHz)2]1/2. Residues with large perturbations ([(Δ15NHz)2 + (Δ1HHz)2]1/2 > 10.0) are shown. Numbers of each bar show their residual numbers. Positions of four EF hands are also indicated under the graph