SAXS data from solutions of the ACT domain of the M. tuberculosis Rel protein in 50 mM Tris-HCl, 350 mM NaCl, 5% glycerol, 1 mM DTT, pH 8.5 were collected using a Bruker NanoStar instrument at Nanyang Technological University (Singapore) equipped with a VÅNTEC 2000 detector at a sample-detector distance of 0.7 m and at a wavelength of λ = 0.134 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 3.30 mg/ml was measured at 15°C. Six successive 300 second frames were collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.