Synchrotron SAXS data from solutions of Lys-Glu mutant RNAP in 20 mM phosphate buffer, 10 mM NaCl, 0.05% NaN3, pH 6.6 were collected on the EMBL P12 beam line at PETRA III (Hamburg, Germany) using a Pilatus 2M detector at a sample-detector distance of 3 m and at a wavelength of λ = 0.124 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). Solute concentrations ranging between 0.8 and 2.6 mg/ml were measured at 20°C. 20 successive 0.050 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. The low angle data collected at lower concentrations were extrapolated to infinite dilution and merged with the higher concentration data to yield the final composite scattering curve.
There is a concentration effect in the concentration series for the sample in 10 mM salt buffer, so we use extrapolation to infinite dilution.
s, nm-1
