Fig. 2.

Using chirality-induced 2D correlation spectroscopy to discriminate between the hairpin structures indistinguishable by NMR. (A) Fifteen-residue β-hairpin peptide Trpzip4. (B) Simulated (red) and experimental (17) (green) linear absorption of amide I vibrational band. (C) Simulated xxxx 2D signals for the aide I band. (Middle and Bottom) Comparison of the simulated spectra for two configurations drawn from the NMR-determined hairpin structure ensembles. Electronic CD (D and G) of the amide band, vibrational CD (E and H) of the amide I band, and xxxy CI 2D signals (F and I) for the amide I band. The CD signals are similar for the two configurations are shown. Major differences of the 2D signals in the cross-peak region indicate specific couplings among vibrational modes.