Department of Biochemistry and Molecular Biophysics, Columbia University, 630 West 168th Street, New York, NY 10032, United States.
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, OH 45267, United States.
J Magn Reson. 2020 Dec;321:106846. doi: 10.1016/j.jmr.2020.106846. Epub 2020 Oct 8.
The Carr-Purcell-Meiboom-Gill (CPMG) NMR relaxation dispersion experiment measures the effective relaxation rate constant during a train of spin-echo pulse sequence elements as a function of the echo time. The CPMG experiment is a powerful method for characterizing chemical and conformational dynamic processes, termed chemical and conformational exchange, on μs-ms time scales, comparable to the experimentally accessible echo times. Approximate theoretical expressions for the effective relaxation rate constant for N-site chemical exchange have been reported (H. Koss, M. Rance, and A. G. Palmer, Biochemistry 57, 4753-4763 (2018)). Expressions for the effective relaxation rate constant have been improved by using the Cayley-Hamilton theorem to obtain simple and accurate approximations of the average Liouvillian for the CPMG experiment. The improved accuracy of the results allows efficient analyses of experimental data. In addition, the relationship is clarified between the approach of Koss and coworkers and that of Jen (1978).
卡尔珀塞尔-米尔-格林（CPMG）NMR 弛豫弥散实验测量了在自旋回波脉冲序列元素的序列中作为回波时间函数的有效弛豫率常数。CPMG 实验是一种强大的方法，可用于在μs-ms 时间尺度上表征化学和构象动态过程，称为化学和构象交换，与实验可达到的回波时间相当。已经报道了用于 N 位化学交换的有效弛豫率常数的近似理论表达式（H. Koss、M. Rance 和 A. G. Palmer，Biochemistry 57, 4753-4763 (2018)）。通过使用 Cayley-Hamilton 定理，获得了 CPMG 实验的平均 Liouvillian 的简单而准确的近似，从而改进了有效弛豫率常数的表达式。结果的准确性得到了提高，从而可以有效地分析实验数据。此外，还澄清了 Koss 及其同事的方法与 Jen（1978）的方法之间的关系。
