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Synchrotron SAXS data from solutions of the apo-RD domain of B. Pertussis adenylate cyclase toxin (CyaA) in 20 mM Hepes, 150 mM NaCl, 2 mM DTT, pH 7.5 were collected on the SWING beam line at SOLEIL (Saint-Aubin, France) using a AVIEX PCCD170170 detector at a sample-detector distance of 1.8 m and at a wavelength of λ = 0.1033 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). In-line size-exclusion chromatography (SEC) SAS was employed. The SEC parameters were as follows: A 50.00 μl sample at 8 mg/ml was injected at a 0.20 ml/min flow rate onto a Agilent Bio SEC-3, 300 Å column at 15°C. 250 successive 1 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 of water. Frames were examined individually and 61 identical frames obtained around the maximum of the elution peak were averaged and further processed. The corresponding concentration was 0.95g/L. The model ensemble of the apo-RD and the final fit to the SAXS pattern (blue dots) was performed using GAJOE analysis. The fit (red line) is the average scattering pattern of the seven conformations shown in the right panel.
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s, nm-1
