Publication details

Theoretical Study of 31P chemical shielding tensors in B-DNA



Year of publication 2004
Type Article in Periodical
Magazine / Source Materials Structure
MU Faculty or unit

Faculty of Science

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Field Physical chemistry and theoretical chemistry
Keywords NMR; DFT; 31P chemical shielding;B-DNA; isotropis chemical shielding; chemical shielding anisotropy; sugar-phosphate backbone
Description In our work, we apply density functional theory (DFT) to assess the influences of the alpha, zeta and epsilon torsional angles, as well as the OPO bond angle in the sugar-phosphate backbone of B-DNA on 31P chemical shielding. In order to conduct NMR parameter calculations, the deMon-NMR code has been used. Our results reveal, that 31P CSI (isotropic chemical shielding) as well as 31P CSA (chemical shielding anisotropy) increase when either alpha or zeta goes up from 270 degs to 330 degs for the former or from 240 degs to 300 degs for the latter. The range of CSI as a function of both torsional angles is of an order of only a few ppm. On the contrary, CSA changes within 30 ppm in the case of alpha and within 10 ppm in the case of zeta. The larger ranges of CSI/CSA obtained for alpha (compared with zeta) indicate higher sensitivity of the 31P chemical shielding to the alpha torsional angle. The plots of CSI/CSA against alpha (zeta) show that the trends of CSI/CSA obtained for various values of zeta=240-300 degs (alpha=270-330 degs) are shifted to higher values when zeta (alpha) increases from 240 degs to 300 degs (from 270 degs to 330 degs). Interestingly, changes in CSI introduced by the epsilon torsional angle are comparable with those introduced by alpha and zeta. However, epsilon leaves CSA almost unaffected. Furthermore, we have uncovered that the trend in the dependence of CSI on alpha correlates with changes in the OPO bond angle caused by changing the alpha torsional angle.
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