SAXS data from solutions of RNase P RNA in 100 mM NaCl, 8.0 mM MgCl2, pH 7.5 were collected using a Rigaku BIOSAXS-2000 instrument at the Center for Cancer Research (National Cancer Institute, Frederick MD USA) equipped with a Rigaku/P100K detector at a sample-detector distance of 0.5 m and at a wavelength of λ = 0.154 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). Solute concentrations ranging between 0.3 and 0.5 mg/ml were measured at 10°C. Eight successive 900 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 concentration were merged with the highest concentration high angle data to yield the final composite scattering curve.
The sample was freshly prepared and the data collected just after SEC separation.