The two-dimensional IR nonlinear spectroscopy of a cyclic penta-peptide in relation to its three-dimensional structure.
A form of two-dimensional (2D) vibrational spectroscopy, which uses two ultrafast IR laser pulses, is used to examine the structure of a cyclic penta-peptide in solution. Spectrally resolved cross peaks occur in the off-diagonal region of the 2D IR spectrum of the amide I region, analogous to those in 2D NMR spectroscopy. These cross peaks measure the coupling between the different amide groups in the structure. Their intensities and polarizations relate directly to the three-dimensional structure of the peptide. With the help of a model coupling Hamiltonian, supplemented by density functional calculations, the spectra of this penta-peptide can be regenerated from the known solution phase structure. This 2D-IR measurement, with an intrinsic time resolution of less than 1 ps, could be used in all time regimes of interest in biology.
Department of Chemistry, The Johnson Foundation for Research in Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Hamm
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Lim
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DeGrado
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Hochstrasser
D000595:Amino Acid Sequence; D003205:Computing Methodologies; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared / Q000379:methods; D014732:Vibration
D009842:Oligopeptides; D010456:Peptides, Cyclic