Detection of slow dynamics by solid-state NMR: Application to L-phenylalanine hydrochloride

New methods for probing dynamical properties of biological macromolecules on the millisecond timescale will enable a better understanding of the structurefunction relationship. In this article, three solid-state NMR detection methods, line-shape analysis, two-dimensional exchange experiments, and a variant of the center-band only detection of exchange (CODEX) experiment called R-CODEX, are used to characterize a crystalline amino acid that serves as a model for motions in solid proteins, L-phenylalanine hydrochloride. The millisecond ring flip motion of the aromatic ring in L-phenylalanine hydrochloride is characterized in detail for the first time. Limitations of these experiments for processes involving submillisecond timescales are also discussed. (c) 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 1422, 2013.