FIGURE 8.

SAXS profiles of Ca²⁺/CaM and Ca²⁺/CaM-Cpep complex. A, SAXS data as I(q) versus q for Ca²⁺/CaM (♢) and the Ca²⁺/CaM-Cpep complex (□) with the GNOM fits (white lines) superposed. The measured data were all placed on an absolute scale using scattering from water but are shown here multiplied on the I(q) axis for clarity. B, P(r) versus r calculated using the data in A and normalized to the ratio of the square of the molecular mass of each protein. The symbols are as for A, and error bars (not shown; corresponding to ± 1 S.D.) are smaller than the symbols. Inset, Guinier plots of the SAXS data for Ca²⁺/CaM (♢) and Ca²⁺/CaM-Cpep complex (□) and linear fits (line) to the data at qR_g < 1.3. C, shape reconstructions of Ca²⁺/CaM and Ca²⁺/CaM-Cpep overlaid with the crystal structure of Ca²⁺/CaM. Crystal structure of Ca²⁺/CaM (PDB 1CLL) is shown in a ribbon diagram, and shape reconstructions of Ca²⁺/CaM alone and Ca²⁺/CaM-Cpep are shown as a gray surface and in black dots, respectively.