Supplementary Figure 5: Cross-validation of the SSNMR structure of α-syn fibrils with electron microscopy and X-ray fiber diffraction.
From: Solid-state NMR structure of a pathogenic fibril of full-length human α-synuclein
(a) Chemical shift comparison of the fibril sample for solid-state NMR before and after washing with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer and sonication for electron microscopy. (b) Expansions of overlaid 2D 13C-13C spectra of the U-13C, 15N α-syn fibril as prepared for solid-state NMR (red) and fibrils washed with HEPES buffer as the samples for electron microscopy (blue). Spectra were acquired at 600 MHz 1H frequency, 13.3 kHz magic-angle spinning (MAS) and 50 ms dipolar-assisted rotational resonance (DARR, Takegoshi, K., Nakamura, S. & Terao, T. 13C-1H dipolar-assisted rotational resonance in magic-angle spinning NMR. Chem. Phys. Lett. 344, 631–637 (2001).). (c) Equatorial intensity plot of the calculated and experimental fiber diffraction pattern of the α-syn fibril. The solid line shows the experimental fiber diffraction pattern (equatorial intensity projected from Figure 4c) compared to the simulated pattern (dotted line) from the atomic coordinates of the structure presented in Figure 3. The simulated pattern recapitulates the main features of the experimental pattern including the fine features near 0.12 Å−1. The correlation coefficient between the two patterns is 0.77, in good agreement with previous amyloid fibril fiber diffraction comparisons.
