31 P spin–lattice and singlet order relaxation mechanisms in pyrophosphate studied by isotopic substitution, field shuttling NMR, and molecular dynamics simulation
31 P spin–lattice and singlet order relaxation mechanisms in pyrophosphate studied by isotopic substitution, field shuttling NMR, and molecular dynamics simulation
复制标题
通过同位素取代、场穿梭核磁共振和分子动力学模拟研究焦磷酸盐中的 31 P 自旋晶格和单重态弛豫机制
DOI：
10.1039/d2cp03801c
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发表时间：
2022
影响因子：
3.3
通讯作者：
Jerschow, Alexej
中科院分区：
文献类型：
--
作者：
Korenchan, David E.;Lu, Jiaqi;Sabba, Mohamed;Dagys, Laurynas;Brown, Lynda J.;Levitt, Malcolm H.;Jerschow, Alexej
核自旋松弛机制通常很难分离和识别，特别是在具有内部柔性的分子中。在这里，我们将实验工作和计算相结合，以确定焦磷酸盐的31P自旋晶格和单态有序(SO)弛豫的主要机制。焦磷酸盐是一个生理相关的分子。利用场穿梭弛豫测量(从2μT到9.4T)和由分子动力学(MD)轨迹计算的速率，我们确定化学位移各向异性(CsA)和自旋旋转是主要机制，分子内和分子间耦合的贡献很小。显著的自旋-旋转相互作用是-PO32−实体围绕桥联P-O键相对快速旋转的结果，并通过MD模拟和量子化学计算相结合的方式进行处理。在没有可调参数的情况下，自旋晶格驰豫得到了很好的预测，对于自旋晶格驰豫，从实验和计算的比较中提取了一个参数(基团自转运动之间的关联系数)。
Nuclear spin relaxation mechanisms are often difficult to isolate and identify, especially in molecules with internal flexibility. Here we combine experimental work with computation in order to determine the major mechanisms responsible for 31P spin–lattice and singlet order (SO) relaxation in pyrophosphate, a physiologically relevant molecule. Using field-shuttling relaxation measurements (from 2 μT to 9.4 T) and rates calculated from molecular dynamics (MD) trajectories, we identified chemical shift anisotropy (CSA) and spin–rotation as the major mechanisms, with minor contributions from intra- and intermolecular coupling. The significant spin–rotation interaction is a consequence of the relatively rapid rotation of the –PO32− entities around the bridging P–O bonds, and is treated by a combination of MD simulations and quantum chemistry calculations. Spin–lattice relaxation was predicted well without adjustable parameters, and for SO relaxation one parameter was extracted from the comparison between experiment and computation (a correlation coefficient between the rotational motion of the groups).