Figure 5
Synchrotron small-angle X-ray scattering data and analysis of MT complexed with 0.5 µM of poly L-lysine 260 kD. Upper solid symbols: Radially averaged scattering intensities of MT complexed with poly L-lysine. The broken curve is the assumed background (Andreu et al., 1992; Fernando-Diaz et al., 1996; Needleman et al., 2004b). Lower open symbols: scattering data of the upper solid symbols following background subtraction. The lower solid curve is the fitted scattering model. The inset shows the variation of the radial electron density, Δρ(r), relative to water of the complex wall, obtained from fitting the scattering data to models of concentric cylinders. r is the distance from the center of the cylinders. The tubulin oligomer coverage, f, obtained from the nonlinear fit is 0.7, as indicated on the right. The +/− charge ratio is 1:2. |