Ottiger M, Delaglio F, Marquardt J L, Tjandra N, Bax A
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892-0520, USA.
J Magn Reson. 1998 Oct;134(2):365-9. doi: 10.1006/jmre.1998.1546.
A simple and effective method is described for simultaneously measuring dipolar couplings for methine, methylene, and methyl groups in weakly oriented macromolecules. The method is a J-modulated 3D version of the well-known [1H-13C] CT-HSQC experiment, from which the J and dipolar information are most accurately extracted by using time-domain fitting in the third, constant-time dimension. For CH2-sites, the method generally yields only the sum of the two individual 13C-1H couplings. Structure calculations are carried out by minimizing the deviation between the measured sum, and the sum predicted for each methylene on the basis of the structure. For rapidly spinning methyl groups the dipolar contribution to the splitting of the outer 13C quartet components can be used directly to constrain the orientation of the C-CH3 bond. Measured sidechain dipolar couplings are in good agreement with an ensemble of NMR structures calculated without use of these couplings.
本文描述了一种简单有效的方法，用于同时测量弱取向大分子中甲氢基、亚甲基和甲基的偶极耦合。该方法是著名的[1H-13C] CT-HSQC实验的J调制3D版本，通过在第三个恒时维度中使用时域拟合，可以最准确地提取J和偶极信息。对于CH2位点，该方法通常仅产生两个单独的13C-1H耦合的总和。通过最小化测量总和与基于结构预测的每个亚甲基总和之间的偏差来进行结构计算。对于快速旋转的甲基，偶极对外部13C四重峰组分分裂的贡献可直接用于约束C-CH3键的取向。测得的侧链偶极耦合与在不使用这些耦合的情况下计算的NMR结构集合高度一致。
