Synchrotron SAXS data from solutions of recombinantly formed monomeric human properdin in 10 mM HEPES pH 7.2, 150 mM NaCl, were collected EMBL-P12 bioSAXS beam line at the PETRAIII storage ring (Hamburg, Germany) equipped with a Pilatus 2M detector (I(s) vs s, where s = 4π sin θ/λ; 2θ is the scattering angle; λ = 0.124 nm). Solute concentrations ranging between 2.7 and 9.1 mg/ml were measured at 20°C. 20 successive 0.05 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 protein concentration. The low angle data collected at lower concentration were merged with the highest concentration high angle data to yield the final composite scattering curve.