Synchrotron SAXS data from solutions of single stranded poly-deoxyadenosine DNA (30mer, dA30) in 200 mM NaCl in 1mM Na MOPS, 200mM NaCl, pH 7 were collected on the G1 beam line at the Cornell High Energy Synchrotron Source (CHESS, Ithaca, NY, USA) using a CCD Finger Lakes CCD detector at a sample-detector distance of 1.8 m and at a wavelength of λ = 0.1 nm (I(s) vs s, where s = 4π sin θ/λ and 2θ is the scattering angle). Solute concentrations ranging between 0.5 and 1.8 mg/ml were measured at 22°C. 20 successive 10 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 and the different curves were scaled for solute concentration. 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.
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