Comparison of quantitative conformer analyses by nuclear magnetic resonance and Raman optical activity spectra for model dipeptides
Language English Country United States Media print-electronic
Document type Comparative Study, Journal Article, Research Support, Non-U.S. Gov't
PubMed
18729424
DOI
10.1021/jp806181q
Knihovny.cz E-resources
- MeSH
- Models, Chemical * MeSH
- Dipeptides chemistry MeSH
- Quantum Theory MeSH
- Magnetic Resonance Spectroscopy methods standards MeSH
- Molecular Conformation MeSH
- Computer Simulation * MeSH
- Spectrum Analysis, Raman methods standards MeSH
- Reference Standards MeSH
- Reproducibility of Results MeSH
- Vibration MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
- Names of Substances
- Dipeptides MeSH
Interpretation of the Raman optical activity (ROA) of peptides is difficult because of molecular flexibility and interaction with the solvent. Typically, simulations and experiments are compared in terms of a qualitative agreement between the spectra. However, on a series of the Pro-Gly, Gly-Pro, Pro-Ala, and Ala-Pro dipeptides more precise conformer ratios could be obtained with the aid of the density functional computations and numerical decomposition of the spectral shapes. All observed transitions were assigned, and the computed transition frequencies were scaled accordingly. Then the populations predicted by the optical spectroscopy agreed within a few percent with an analysis of the spin-spin coupling constants based on the Karplus equations, which was confirmed also by a comparison of calculated and experimental NMR couplings. The results are supported by molecular dynamics simulations and related to the previous conformational studies of similar molecules.
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