Figure 1.

(A) Overlay of the ¹⁵N–¹H HSQC spectra recorded at 800 MHz for monomeric Aβ^1–40 (red) and Aβ^1–42 (black) peptides at 277 K. Assignments of the backbone amide cross-peaks are colored gray for residues with nearly identical chemical shifts in the two peptides, while labels in red and black (for Aβ^1–40 and Aβ^1–42, respectively) correspond to residues with significantly different chemical shifts in the two peptides. Secondary chemical shifts for (B) ¹³C′, (C) ¹³C^α, and (D) ¹H^α nuclei of Aβ^1–40 (red) and Aβ^1–42 (black) were derived using random coil values and correction factors of Poulsen and co-workers.^36,37