Supplementary Figure 7: 2D 13C-13C correlation spectra of diluted samples indicate the intermolecular nature of all long-range correlations and the homodimer interfaces in the plane perpendicular to the fibril axis.
From: The peptide hormone glucagon forms amyloid fibrils with two coexisting β-strand conformations
a, 500 ms PDSD spectra of sample 1 without (black) and with (red) dilution. b, 500 ms CORD spectra of sample 3 without (black) and with (red) dilution. The 1D cross sections of V23 Cα and T5 Cβ show reduced intensities for V23 and T5 cross peaks compared to the diagonal peaks due to dilution, indicating that in the undiluted sample, these cross peaks result from both intramolecular and intermolecular contacts. Sequential cross peaks such as T5–F6 have similar intensity reduction as the intra-residue peaks, indicating that these sequential contacts also have both intramolecular and intermolecular contributions. For comparison, long-range V23–S8 and M27–T5 correlations are suppressed by dilution, indicating that these correlations result from antiparallel intermolecular packing.
