Brumovská Eva, Sychrovský Vladimír, Vokácová Zuzana, Sponer Jirí, Schneider Bohdan, Trantírek Lukás
Faculty of Science, University of South Bohemia and Biology Centre AS CR v.v.i., Branisovská 31, 370 05, Ceské Budejovice, Czech Republic.
J Biomol NMR. 2008 Nov;42(3):209-23. doi: 10.1007/s10858-008-9278-7. Epub 2008 Oct 14.
Density functional theory was employed to study the dependence of 13C and 15N magnetic shielding tensors on the glycosidic torsion angle (chi) and conformation of the sugar ring in 2'-deoxyadenosine, 2'-deoxyguanosine, 2'-deoxycytidine, and 2'-deoxythymidine. In general, the magnetic shielding of the glycosidic nitrogens and the sugar carbons was found to depend on both the conformation of the sugar ring and chi. Our calculations indicate that the magnetic shielding anisotropy of the C6 atom in pyrimidine and the C8 atom in purine bases depends strongly on chi. The remaining base carbons were found to be insensitive to both sugar pucker and chi re-orientation. These results call into question the underlying assumptions of currently established methods for interpreting residual chemical shift anisotropies and 13C and 15N auto- and cross-correlated relaxation rates and highlight possible limitations of DNA applications of these methods.
采用密度泛函理论研究了2'-脱氧腺苷、2'-脱氧鸟苷、2'-脱氧胞苷和2'-脱氧胸苷中13C和15N磁屏蔽张量对糖苷扭转角（χ）和糖环构象的依赖性。一般来说，发现糖苷氮和糖碳的磁屏蔽取决于糖环的构象和χ。我们的计算表明，嘧啶中C6原子和嘌呤碱基中C8原子的磁屏蔽各向异性强烈依赖于χ。发现其余的碱基碳对糖的折叠和χ重取向均不敏感。这些结果对目前用于解释残余化学位移各向异性以及13C和15N自相关和交叉相关弛豫率的既定方法的基本假设提出了质疑，并突出了这些方法在DNA应用中的可能局限性。
