FIGURE 3. Effect of PEP-19 polypeptides on the global conformation of CaM.

The fluorescence emission spectrum of CaMD/A was compared in the absence or presence of PEP-19, PEP(28–62), PEP(39–62), or CKII-(293–312). Spectra were collected in solutions of 10 mM MOPS, pH 7.5, 100 mM KCl, 0.1 mM CaCl₂, and 1 μM CaMD/A. All PEP-19 derivatives were present at 60 μM, whereas CKII-(293–312) was present at 4 μM. The excitation wavelength was 335 nm, and spectra were corrected for the effect of the various polypeptides on fluorescence from CaM labeled with the FRET donor alone as described under “Experimental Procedures.”