Algebraic expressions for Carr-Purcell-Meiboom-Gill relaxation dispersion for N-site chemical exchange

J Magn Reson. 2020 Dec:321:106846. doi: 10.1016/j.jmr.2020.106846. Epub 2020 Oct 8.

Abstract

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).

Keywords: Bloch-McConnell equation; Conformational exchange; Dynamics; Kinetics; NMR spectroscopy; Rotating-frame relaxation; Spin-echo.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Algorithms
  • Computer Simulation
  • Data Interpretation, Statistical
  • Macromolecular Substances*
  • Models, Theoretical
  • Nuclear Magnetic Resonance, Biomolecular / methods*
  • Sensitivity and Specificity

Substances

  • Macromolecular Substances