Two-Dimensional Infrared (2DIR) Spectroscopy of the Peptide Beta3s Folding

Probing
the underlying free-energy landscape, pathway, and mechanism
is the key to understanding protein folding in theory and experiment.
Time-resolved two-dimensional infrared (2DIR) with femtosecond laser
pulses has emerged as a powerful tool for investigating the protein
folding dynamics on much faster time scales than possible by NMR.
We have employed molecular dynamics simulations to compute 2DIR spectra
of the folding process of a peptide, Beta3s. Simulated nonchiral and
chiral 2DIR signals illustrate the variation of the spectra as the
peptide conformation evolves along the free-energy landscape. Chiral
spectra show stronger changes than the nonchiral signals because cross
peaks caused by the formation of the β-sheet are clearly resolved.
Chirality-induced 2DIR may be used to detect the folding of β-sheet
proteins with high spectral and temporal resolution.