Figure 3.

(A) Normalized ATR FT-IR spectra of raw solid samples of H, A–B, and B–A peptides. (B) Normalized solvent-subtracted transmission FT-IR spectra of H, A–B, and B–A peptides dissolved in acidified DMSO/D₂O solution. Solid samples were initially dissolved in pure DMSO at 1.1 wt/vol % peptide concentration (for 18 h at 37 °C) followed by addition of 1/9 vol of D₂O, pD 1.64, and 2 h incubation at 37 °C prior to spectral measurements.