Synchrotron SAXS data from solutions of nonstructural protein sigma NS (apoprotein) in 25 mM HEPES, 150 mM NaCl, pH 7.5 were collected on the B21 beam line at the Diamond Light Source storage ring (Oxfordshire, UK) using a Pilatus 2M detector at a sample-detector distance of 3.9 m and at a wavelength of λ = 0.1 nm (l(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.