(A) CD spectra for peptide designs reveal a random coil structure for rc and β-structure spectrum with a bit of random coil for β. In contrast, α1, α2 and α3 have largely featureless CD spectra with some random coil content expected to arise from the turns and tail residues. Note the different scales for the y-axes. All spectra are presented as molar ellipticity, highlighting the difference in intensity of the random coil component for each design compared with the rc spectrum. (B) FTIR spectra of the peptide designs, displayed as both absorbance (black line) and the second derivative (colored line), correlate well with the CD spectra. The β design shows a strong signal at 1632 cm−1, as expected for β-structure. The α-sheet designs have signals near 1640 and 1675–1680 cm−1 and the absorption is more intense for α1 and α2. (C) Fingerprint (top) and NH region (bottom) of the 1H NOESY spectra for α1. Sequential assignments are shown in red and multiple sequential NOEs are observed and labeled. (D) Fingerprint (top) and NH region (bottom) of the 1H NOESY spectra for α3. The NH region reflects the predominance of NH–NH interactions and lack of other main-chain interactions characteristic of the common secondary structures. Mapping backbone NOEs on computational models as green bars (E, α1 and F, α3) reveal in-plane alignment of the peptide groups along the majority of the sheet. NOEs in the turn regions determined whether the carbonyl or amide hydrogens pointed up in the structures as oriented in the figure (N-terminus top left). Cα, C, N, H and O atoms are shown in gray, gray, blue, white and red, respectively.