Figure 5.

Dynamics measurements. (a and b) ¹⁵N longitudinal relaxation for (a) residues in the htt^NT α-helix of htt^NTQ₃₀P₁₀K₂ and (b) residue Q10 of the polyQ amyloid core of K₂Q₁₁PGQ₁₁D₂. (a) Relaxation curves are shown for the unfrozen sample (red) and frozen sample (blue). (b) ¹⁵N longitudinal relaxation curves at 275 K for conformers “a” and “b” of Q10 in unfrozen polyQ peptide K₂Q₁₁PGQ₁₁D₂ (described in ref (48)). Data were obtained as 1D ¹⁵N spectra at 19–22 kHz MAS. (c and d) N–H dipolar recoupling curves for M8 and A10 in the htt^NT of htt^NTQ₃₀P₁₀K₂ fibrils, obtained on unfrozen (287 K, red) or frozen (250 K, blue) samples, respectively. (e) N–H coupling measurements of the polyQ amyloid core, showing separate curves for both conformers of the uniformly ¹³C- and ¹⁵N-labeled residue Q10 in unfrozen (275 K) fibrillar K₂Q₁₁PGQ₁₁D₂. Panels c–e used an R18₁⁷ symmetry sequence at 10 kHz MAS. All data were acquired at 600 MHz (¹H).