Figure 7.

MAS NMR of Phe19–Leu34 contacts in Aβ monomers and fibrils of Aβ40-WT, Aβ40-Dutch, Aβ40-Iowa, and Aβ42-WT. (A) Two-dimensional ¹³C DARR NMR spectrum of Aβ40-Iowa labeled with ring-¹³C-Phe and U-¹³C-Leu34. (B and C) Rows taken through the diagonal resonance of ring-¹³C-Phe at time zero and 2 weeks, respectively, for Aβ40-Iowa. (D and E) Relative intensities of the ring-¹³C-Phe–U-¹³C-Leu34 cross peaks corresponding to the well-resolved Leu34 ¹³C=O and ¹³CH₃ resonances at time zero and 2 weeks, respectively, relative to the ring-¹³C-Phe diagonal resonance. The strongest cross-peak relative to the ring-¹³C-Phe diagonal resonance was observed for Aβ40-Dutch, which was set equal to 1.0, at both time points. For the experiments using incubation for 2 weeks, the temperature was maintained at 37 °C. Errors shown are relative to the spectral noise.