Two-dimensional infrared spectral signatures of [3.sub.10-] and [alpha]-helical peptides

The two-dimensional infrared (2D- IR) spectra of [C.sub.alpha]-alkylated model octapeptides Z-[(Aib).sub.8]-OtBu, Z-[(Aib).sub.5]-L-Leu-[(Aib).sub.2]-OMe and Z-[[L-([alpha]MeVal)].sub.8]-OtBu in the amide I region is evaluated to determine the 2D spectral signatures features of [3.sub.10-] and [alpha]-helical conformations. The sensitivity of cross-peak trends to various helical conformations and the dependence of chain lengths of the special characteristics for short [3.sub.10-] and alpha-helices are described.