Relationships between 31P Chemical Shift Tensors and Conformation of Nucleic Acid Backbobe: A DFT Study
| Authors | |
|---|---|
| Year of publication | 2007 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Physical Chemistry B |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | NMR chemical shift tensor 31P nucleic acids |
| Description | Density functional theory (DFT) has been applied to study the conformational dependence of 31P chemical shift tensors in B-DNA. The gg and gt conformations of backbone phosphate groups representing BI- and BII-DNA have been examined. Calculations have been carried out on static models of dimethyl phosphate (dmp) and dinucleoside-3',5'-monophosphate with bases replaced by hydrogen atoms in vacuo as well as in an explicit solvent. Trends in 31P chemical shift anisotropy (CSA) tensors with respect to the backbone torsion angles alpha, zeta, beta, and epsilon are presented. Although these trends do not change qualitatively upon solvation, quantitative changes result in the reduction of the chemical shift anisotropy. For and in the range from 270 deg to 330 deg and from 240 deg to 300 deg, respectively, the delta22 and delta33 principal components vary within as much as 30 ppm, showing a marked dependence on backbone conformation. The calculated 31P chemical shift tensor principal axes deviate from the axes of O-P-O bond angles by at most 5 deg. For solvent models, our results are in a good agreement with experimental estimates of relative gg and gt isotropic chemical shifts. Solvation also brings the theoretical iso of the gg conformation closer to the experimental gg data of barium diethyl phosphate. |
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