Journal article
Dihedral Angles of Trialanine in D2O Determined by Combining FTIR and Polarized Visible Raman Spectroscopy
Journal of the American Chemical Society, v 123(39), pp 9628-9633
03 Oct 2001
PMID: 11572684
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Abstract
We have measured the polarized visible Raman and FTIR spectra of trialanine and triglycine in D2O at acid, neutral, and alkaline pD. From the Raman spectra we obtained the isotropic and the anisotropic scattering. A self-consistent spectral analysis of the region between 1550 and 1800 cm-1 was carried out to obtain the intensities, frequencies, and halfwidths of the respective amide I bands. A model was developed by means of which the intensity ratios of the amide I bands in all spectra and the respective frequency differences were utilized to determine the orientational angle θ between the peptide groups and the strength of excitonic coupling between the corresponding amide I modes. By exploiting results from a recent ab initio study on triglycine (Torii, H; Tasumi, M. J. Raman Spectrosc. 1998, 29, 81), we used these parameters to determine the dihedral angles φ and ψ between the peptide groups. Our results show that trialanine adopts a 31-helical structure in D2O for all of its three protonation states. The structure is insensitive to the carboxylate protonation and changes only slightly with N-terminal protonation. Triglycine is structurally more heterogeneous in the zwitterionic and the cationic state. Our spectral analysis suggests that 31-helices coexist with right-handed α-helical and/or with β-turn conformations. The N-terminal protonation stabilizes the 31-structure. Our study provides compelling evidence that tripeptides adopt stable conformations in aqueous solution and that they are suitable model systems to investigate the initiation of secondary structure formation.
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Details
- Title
- Dihedral Angles of Trialanine in D2O Determined by Combining FTIR and Polarized Visible Raman Spectroscopy
- Creators
- Reinhard Schweitzer-StennerFatma EkerQing HuangKai Griebenow
- Publication Details
- Journal of the American Chemical Society, v 123(39), pp 9628-9633
- Publisher
- American Chemical Society; Washington, DC
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000171407800016
- Scopus ID
- 2-s2.0-0035802365
- Other Identifier
- 991014878591004721
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- Web of Science research areas
- Chemistry, Multidisciplinary