Amide I’-II’ 2D IR spectroscopy provides enhanced protein secondary structural sensitivity
Name
Protein Amide I-II Final.pdf
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1.3 MB
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Author(s)
DeFlores, Lauren P.
Ganim, Ziad
Nicodemus, Rebecca A.
Tokmakoff, Andrei
Date Issued
February 2009
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society
Citation
DeFlores, Lauren P. et al. “Amide I′−II′ 2D IR Spectroscopy Provides Enhanced Protein Secondary Structural Sensitivity.” Journal of the American Chemical Society 131.9 (2009): 3385–3391.
Version
Author's final manuscript
Abstract
We demonstrate how multimode 2D IR spectroscopy of the protein amide I′ and II′ vibrations can be used to distinguish protein secondary structure. Polarization-dependent amide I′−II′ 2D IR experiments on poly-l-lysine in the β-sheet, α-helix, and random coil conformations show that a combination of amide I′ and II′ diagonal and cross peaks can effectively distinguish between secondary structural content, where amide I′ infrared spectroscopy alone cannot. The enhanced sensitivity arises from frequency and amplitude correlations between amide II′ and amide I′ spectra that reflect the symmetry of secondary structures. 2D IR surfaces are used to parametrize an excitonic model for the amide I′−II′ manifold suitable to predict protein amide I′−II′ spectra. This model reveals that the dominant vibrational interaction contributing to this sensitivity is a combination of negative amide II′−II′ through-bond coupling and amide I′−II′ coupling within the peptide unit. The empirically determined amide II′−II′ couplings do not significantly vary with secondary structure: −8.5 cm−1 for the β sheet, −8.7 cm−1 for the α helix, and −5 cm−1 for the coil.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/ja8094922
