X-ray synchrotron radiation scattering data, I(s) vs s, (s = 4πsinθ/λ, and 2θ is the scattering angle) were collected from a sample of bovine serum albumin using continuous-flow size-exclusion chromatography SAXS (SEC-SAXS) at the SWING beamline (wavelength, λ: 0.1033 nm) on the Synchrotron SOLEIL (Gif sur Yvette, France). The BSA sample (Sigma-Aldrich A7906) was dissolved in Hepes 20mM pH7.4 NaCl 150mM. The solution was stored at 5°C for a few days before measurements, conditions that allow for a well-documented self-association of the protein into dimers, trimers and higher order oligomers. 50 µL of 10.8 mg/mL solution were loaded onto a BioResolve SEC column 200 Å, 2.5 µm, 4.6 x 300 mm (from WatersTM) at a flow rate of 0.3 ml/min. A total of 720 x 0.99 second SAXS data frames were recorded throughout the BSA elution (180 before void volume and 540 after void volume) .
After background solvent corrections, the 250 first frames after the void volume were analyzed. SVD analysis performed in US-SOMO or RAW suggests that four species are necessary to account for the complete dataset. Three different methods (EFA, REGALS, US-SOMO) were tested to deconvolute the various species.
The presented SAXS curve is the peak3 of the US-SOMO analysis corresponding to the trimer of BSA according to the Molecular Weight.
The 250 subtracted frames from the SEC-SAXS measurements and the results of the three methods are available in the zip file.