Determination of the glycosidic bond angle χ in RNA from cross-correlated relaxation of CH dipolar coupling and N chemical shift anisotropy
Determination of the glycosidic bond angle χ in RNA from cross-correlated relaxation of CH dipolar coupling and N chemical shift anisotropy
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DOI：
10.1021/ja0367041
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发表时间：
2004-02-25
影响因子：
15
通讯作者：
Schwalbe, H
中科院分区：
文献类型：
--
作者：
Duchardt, E;Richter, C;Schwalbe, H
介绍了一种新的异核磁共振脉冲序列——定量伽玛（HCN）实验，用于测定C-13， n -15标记的寡核苷酸中的糖苷扭转角chi。Gamma（HCN）实验允许测量CH偶极子-偶极子，N化学位移各向异性交叉相关弛豫率(嘧啶的Gamma(C1H1;N1)（DD，CSA）和Gamma(c2h2,N1)（DD，CSA）和嘌呤的Gamma(C1H1),(DD，CSA)（N9）和Gamma（c2h2,N9)(DD，CSA)）。基于固态核磁共振实验确定的N-15化学位移张量，对这些γ -速率对chi的依赖性的核苷酸特异性参数化（Stueber， D.; Grant， D. M. J. Am.）。化学。Soc. 2002, 124, 10539-10551)。对于已知结构的14-mer和30-mer RNA，发现伽玛（HCN）实验为角chi的变化提供了一个非常敏感的参数，并且允许以10度左右的精度限制chi，残基不进行构象平均。因此，除了由(3)J（C，H）耦合常数得到的数据外，Gamma（HCN）实验也可用于chi的测定。如30-mer RNA所示，导出的扭转角信息可以作为附加约束，改进RNA结构计算。
A new heteronuclear NMR pulse sequence, the quantitative Gamma(HCN) experiment, for the determination of the glycosidic torsion angle chi in C-13,N-15-labeled oligonucleotides is described. The Gamma(HCN) experiment allows measurement of CH dipole-dipole, N chemical shift anisotropy cross-correlated relaxation rates (Gamma(C1H1;N1)(DD,CSA) and Gamma(C2'H2',N1)(DD,CSA) for pyrimidines and Gamma(C1'H1'),(DD,CSA)(N9) and Gamma(C2'H2',N9)(DD,CSA) for purines). A nucleotide-specific parametrization for the dependence of these Gamma-rates on chi based on N-15 chemical shift tensors determined by solid-state NMR experiments on mononucleosides (Stueber, D.; Grant, D. M. J. Am. Chem. Soc. 2002, 124, 10539-10551) is presented. For a 14-mer and a 30-mer RNA of known structures, it is found that the Gamma(HCN) experiment offers a very sensitive parameter for changes in the angle chi and allows restraining of chi with an accuracy of around 10 degrees for residues which do not undergo conformational averaging. Therefore, the Gamma(HCN) experiment can be used for the determination of chi in addition to data derived from (3)J(C,H)-coupling constants. As shown for the 30-mer RNA, the derived torsion angle information can be incorporated as additional restraint, improving RNA structure calculations.