Two-dimensional infrared measurements of the coupling between amide modes of an α-helix

The 2D IR spectra of doubly isotopically substituted α-helices with 13C 16O and 13C 18O labels enabled the couplings between amide-I modes separated by one, two and three residues to be measured. The magnitudes and signs of couplings between the isotopomers and between them and the helix exciton b...

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Bibliographic Details
Published in:Chemical physics letters 2003-12, Vol.382 (5), p.586-592
Main Authors: Fang, C., Wang, J., Charnley, A.K., Barber-Armstrong, W., Smith III, A.B., Decatur, S.M., Hochstrasser, R.M.
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
General aspects
Miscellaneous
Molecular biophysics
Proteins
Structure and bonding
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Summary:The 2D IR spectra of doubly isotopically substituted α-helices with 13C 16O and 13C 18O labels enabled the couplings between amide-I modes separated by one, two and three residues to be measured. The magnitudes and signs of couplings between the isotopomers and between them and the helix exciton band states confirm that the states of the helix and isotopomers are delocalized. The results are compared with simulations. The off-diagonal anharmonicities agree reasonably with a set of couplings that derive from transition charge interactions except for nearest neighbors for which the coupling is modified by through bond interactions.
ISSN:0009-2614
1873-4448
DOI:10.1016/j.cplett.2003.10.111