Peptide Secondary Structure Determination by Three-Pulse Coherent Vibrational Spectroscopies:  A Simulation Study

Amide I mode vibrational spectra of four ideal secondary structural motiffs of peptides, α helix, 3 10 helix, parallel β sheet, and antiparallel β sheet, in response to three infrared pulses with wavevectors k 1, k 2, and k 3 are simulated using a vibrational exciton model. Correlation plots of the signals generated at − k 1 + k 2 + k 3 and + k 1 + k 2 − k 3 show a characteristic peak pattern for each motiff. Resolution is enhanced by applying specific polarization configurations of the optical fields to oriented peptides.