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Synchrotron SAXS
data from solutions of
Metal-bound hETHE1
in
50 mM Tris 150 mM NaCl 2 mM TCEP, pH 8
were collected
on the
EMBL X33 beam line
at the DORIS III, DESY storage ring
(Hamburg, Germany)
using a Pilatus 1M-W detector
at a sample-detector distance of 2.7 m and
at a wavelength of λ = 0.15 nm
(I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle).
Solute concentrations ranging between 2 and 5 mg/ml were measured
at 9°C.
Four successive
30 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 low angle data collected at lower concentration were merged with the highest concentration high angle data to yield the final composite scattering curve.
Metal-bound hETHE1 was shown by SAXS to be a globular protein compatible with a dimeric hETHE1 in solution. The calculated scattering pattern from a high resolution model of dimeric ETHE1 is in a very good agreement (χ2 value of 1.5) with the experimental data from hETHE1. The low resolution shape of metal-bound hETHE1 was reconstructed ab initio using DAMMIN with P2 symmetry imposed. The ab initio model fits the experimental data with a discrepancy χ2 = 1.3 and is in a good agreement with the high resolution ETHE1 structure.
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s, nm-1
