We are interested in the effect that infrared light has on proteins in general, especially that of high intensity infrared using 2-dimensional nonlinear spectroscopy to probe protein structure and dynamics. The 3-dimensional structure of proteins and their dynamics form the basis of biological function. However, these structural fluctuations and their relationship to protein functions are not well understood. Recent use of two-dimensional (2D) nonlinear spectroscopy, which employs two ultrafast infrared (IR) lasers, provides a novel method to study polypeptide structure and dynamics. Dr. Robin Hochstrasser and his coworkers have used 2D IR spectroscopy to examine the structural fluctuations of a cyclic-penta-peptide in solution. I will be joining the team's ongoing project to use 2D nonlinear spectroscopy to study structures and dynamics of biomolecules. The team is developing new instrumentations, devising methods to invert the 2D IR data into three-dimensional map s. Theore tical methods such as ab-initio calculations of chemical bond energies and vibrations are being used. Attempts are being made to obtain extra information for this inversion from isotropic labeling and solvent shifts experiments. Although x-ray and NMR provide knowledge of the distributions of structures of peptides and proteins, they indicate little about the time scales of their fluctuations. However, 2D IR spectroscopy measures chemical processes on the ps time scale allowing resolution of structural motions over essentially all time scales of interest in biology, for example during all stages of protein folding.
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