31P Chemical Shift Tensors for Canonical and Non-canonical Conformations of Nucleic Acids: A DFT Study and NMR Implications

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31P Chemical Shift Tensors for Canonical and Non-canonical Conformations of Nucleic Acids: A DFT Study and NMR Implications

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作者：Jana Pp ; //pubs.acs.org/images/entities/rcaron.gif" border="0">ecechtp ; //pubs.acs.org/images/entities/ecaron.gif" border="0">lová ; Petr Padrta ; Mark&eacute ; ta L. Munzar
刊名：Journal of Physical Chemistry B
出版年：2008
出版时间：March 20, 2008
年：2008
卷：112
期：11
页码：3470 - 3478
全文大小：149K
年卷期：v.112,no.11(March 20, 2008)
ISSN：1520-5207

文摘

P>31P chemical shift anisotropy (CSA) tensors have been calculated for a set of selected DNA and RNA backboneconformations using density functional theory. The set includes canonical A-RNA, A-DNA, B_I-DNA, B_II-DNA, Z_I-DNA, and Z_II-DNA as well as four A-RNA-type, seven non-A-RNA-type, and three non-canonicalDNA conformations. Hexahydrated dimethyl phosphate has been employed as a model. The ³¹P chemicalshift tensors obtained are discussed in terms of similarities in the behavior observed for gauche-gauche (gg)and gauche-trans (gt) conformations around the P-O bonds. We show that torsion angles

pha.gif" BORDER=0> and

are majordeterminants of the isotropic chemical shift

_iso and of the

pcbfk/112/i11/eqn/jp076073ne10001.gif"> component of the traceless chemical shifttensor, which is revealed in separate ranges of both

_iso and

pcbfk/112/i11/eqn/jp076073ne10002.gif"> for gg- and gt-conformers, respectively.A clear distinction between the two conformation types has not been found for the

pcbfk/112/i11/eqn/jp076073ne10003.gif"> and

pcbfk/112/i11/eqn/jp076073ne10004.gif">components, which is attributed to their different directional properties. The ³¹P CSA tensors exhibitconsiderable variations resulting in large spans of ~16 ppm for

pcbfk/112/i11/eqn/jp076073ne10005.gif"> and ~22 ppm for

pcbfk/112/i11/eqn/jp076073ne10006.gif"> and

pcbfk/112/i11/eqn/jp076073ne10007.gif">. Weexamine the consequences of the CSA variations for predicting the chemical shift changes upon partialalignment

^csa and for the values of CSA order parameters extracted from the analysis of ³¹P NMR relaxationdata. The theoretical ³¹P CSA tensors as well as the experimental ³¹P CSA tensor of barium diethyl phosphate(BDEP) are used to calculate

^csa for two eclipsed orientations of the CSA and molecular alignment tensors.Percentage differences between the CSA order parameters obtained using the theoretical ³¹P CSA tensors andthe experimental ³¹P CSA tensor of BDEP, respectively, are also determined.

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