Relationships between 31P Chemical Shift Tensors and Conformation of Nucleic Acid Backbone: A DFT Study

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• 作者：Jana Psrc="http ; //pubs.acs.org/images/entities/rcaron.gif" border="0">ecechtsrc="http ; //pubs.acs.org/images/entities/ecaron.gif" border="0">lov&aacute ; Marké ; ta L. Munzarov&aacute ; P
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：March 15, 2007
• 年：2007
• 卷：111
• 期：10
• 页码：2658 - 2667
• 全文大小：743K
• 年卷期：v.111,no.10(March 15, 2007)
• ISSN：1520-5207

文摘

Density functional theory (DFT) has been applied to study the conformational dependence of ³¹P chemicalshift tensors in B-DNA. The gg and gt conformations of backbone phosphate groups representing B_I- andB_II-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 inan explicit solvent. Trends in ³¹P chemical shift anisotropy (CSA) tensors with respect to the backbone torsionangles s/gifchars/alpha.gif" BORDER=0>, s/gifchars/zeta.gif" BORDER=0 >, s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">, and s/gifchars/epsilon.gif" BORDER=0 > are presented. Although these trends do not change qualitatively upon solvation,quantitative changes result in the reduction of the chemical shift anisotropy. For s/gifchars/alpha.gif" BORDER=0> and s/gifchars/zeta.gif" BORDER=0 > in the range from270s/entities/deg.gif"> to 330s/entities/deg.gif"> and from 240s/entities/deg.gif"> to 300s/entities/deg.gif">, respectively, the s/gifchars/delta.gif" BORDER=0 >₂₂ and s/gifchars/delta.gif" BORDER=0 >₃₃ principal components vary within as muchas 30 ppm, showing a marked dependence on backbone conformation. The calculated ³¹P chemical shifttensor principal axes deviate from the axes of O-P-O bond angles by at most 5s/entities/deg.gif">. For solvent models, ourresults are in a good agreement with experimental estimates of relative gg and gt isotropic chemical shifts.Solvation also brings the theoretical s/gifchars/delta.gif" BORDER=0 >_iso of the gg conformation closer to the experimental gg data of bariumdiethyl phosphate.