SAXS data from solutions of chloroplast FOF1-ATP synthase from Spinacia oleracea in 350 mM NaCl, 30 mM HEPES, 2 mM MgCl2, 0.04% (w/v) tPCC-α-M, pH 8 were collected using a Rigaku MicroMax 007-HF instrument at the Moscow Institute of Physics and Technology (MIPT; Dolgoprudny, Russian Federation) equipped with a Multiwire gas-filled ASM DTR Triton 200 detector at a sample-detector distance of 2 m and at a wavelength of λ = 0.154 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 5.00 mg/ml was measured at 20°C. One 5400 second frame was collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.
The protein of study is a chloroplast FOF1-ATP synthase (cFOF1) from Spinacia oleracea solubilized in 0.04% (w/v) 4-trans-(4-trans-Propylcyclohexyl)-cyclohexyl α-maltoside (tPCC-α-M). SAXS data confirm that cFOF1 purified by anion-exchange chromatography and incubated at 350 mM NaCl is a mixture of monomers and dimers with approximate volume fractions 65% and 35%, respectively. Dimers are formed by F1/F1 contacts (presumably via δ-subunit).
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