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X-ray in house radiation scattering data from solutions of the two-componentsystem ComD-ComE in 20 mM Tris 200 mM NaCl, 5% (vol/vol) glycerol and 5 mM β-mercaptoethanol were collected on the Bruker Nanostar camera (Orsay, France) using a VANTEC detector (s = 4π sin θ/λ, where 2θ is the scattering angle). Different solute concentrations in the range 0.40-1.10 mg/ml were measured. 32 successive 1200 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 scattered intensities were displayed on an absolute scale (cm-1) using the scattering by water. The low angle data collected were merged with the highest concentration high angle data to yield the final composite scattering curve.
Use of SAXS to describe the interaction between ComD and ComE, the two-component system which regulates the competence in S. pneumoniae.
The molecular weight is not estimated from I(0) due to the absence of tryptophan in ComE. It is obtained from the macromolecule volume by using the method developed by Craievich's team (the SAXS Mow program).
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s, nm-1
