Synchrotron SAXS data from solutions of antitoxin HigA-2 in 20 mM Tris pH 8, 200 mM NaCl were collected on the SWING beam line at SOLEIL (Saint-Aubin, France) using a AVIEX PCCD170170 detector at a sample-detector distance of 1.1 m and at a wavelength of λ = 0.1033 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). In-line size-exclusion chromatography (SEC) SAS was employed. The SEC parameters were as follows: A 40.00 μl sample at 3.6 mg/ml was injected at a 0.20 ml/min flow rate onto a Shodex KW402.5-4F column at 15°C. 250 successive 0.750 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.