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SAXS measurements were performed at the SAXS2 beam line located at the Brazilian Synchrotron Light Laboratory (LNLS), Campinas, São Paulo, Brazil. The X-ray scattering data (I(s) vs s, where s = 4πsinθ/λ and 2θ is the scattering angle; λ = 0.1488 nm) were acquired using a two-dimension position-sensitive MARR-CCD detector and a sample-to-detector distance of ~1000 mm, corresponding to the q-range 0 < q < 0.35. In order to checking for protein aggregation or concentration-dependent effects, samples were prepared at various protein concentrations (2.5 mg/mL, 3 mg/mL and 5 mg/mL) in the buffer 25 mM Tris-HCl (pH 7.5), containing 150 mM NaCl, 2 mM EDTA and 1 mM β-mercaptoethanol. Samples were exposed to X-ray at different time frames (5 x 30 seconds, and 180 seconds) to investigate for X-ray damage. No radiation damage or concentration-dependent effect were observed. The model depicts the averaged spatial representation of the protein (DAMFILT occupancy and volume-corrected bead model).
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s, nm-1
