Figure 3
SAXS scattering curves, Kratky representation and relative pair distance distribution functions.
(A) Scattering curves, revealing intensity on a logarithmic scale, against the scattering vector q (q = 4π sin θ/λ, 2θ equals the scattering angle). Transthyretin (TTR) prior to fibrillation (red) is superposed with scattering curves recorded 3½ minutes (black) and 10 minutes (dotted) after initiation. Furthermore, the measured scattering curve of an unfolded TTR monomer is shown in grey. The inset shows the scattering curve of TTR prior to fibrillation (red) fitted to the calculated curve from the tetrameric crystal structure (using the crystallographic coordinates 1TTA.pdb). (B) Kratky representation (I(q)*q2 versus q) for tetrameric TTR prior to initiation (black) and the considerably unfolded TTR monomer in 11% acetic acid (grey). It is evident that TTR prior to initiation primarily consists of folded protein while the Kratky representation of TTR in 11% acetic acid corresponds to a Gaussian coil. (C) Relative pair distance distribution function (P(r)) of tetrameric TTR in dH2O with a Dmax of 7.2 nm (black) and TTR in 11% acetic acid with a Dmax of 12 nm (dashed). The P(r) functions are scaled to a maximum value of 1.
