Protein dynamics in the solid state from 2H NMR line shape analysis: A consistent perspective

Eva Meirovitch, Zhichun Liang, Jack H. Freed

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Deuterium line shape analysis of CD3 groups has emerged as a particularly useful tool for studying microsecond-millisecond protein motions in the solid state. The models devised so far consist of several independently conceived simple jump-type motions. They are comprised of physical quantities encoded in their simplest form; improvements are only possible by adding yet another simple motion, thereby changing the model. The various treatments developed are case-specific; hence comparison among the different systems is not possible. Here we develop a new methodology for 2H NMR line shape analysis free of these limitations. It is based on the microscopic-order-macroscopic-disorder (MOMD) approach. In MOMD motions are described by diffusion tensors, spatial restrictions by potentials/ordering tensors, and geometric features by relative tensor orientations. Jump-type motions are recovered in the limit of large orientational potentials. Model improvement is accomplished by monitoring the magnitude, symmetry, and orientation of the various tensors. The generality of MOMD makes possible comparison among different scenarios. CD3 line shapes from the Chicken Villin Headpiece Subdomain and the Streptomyces Subtilisin Inhibitor are used as experimental examples. All of these spectra are reproduced by using rhombic local potentials constrained for simplicity to be given by the L = 2 spherical harmonics, and by axial diffusion tensors. Potential strength and rhombicity are found to be ca. 2-3 kBT. The diffusion tensor is tilted at 120° from the C-CD3 axis. The perpendicular (parallel) correlation times for local motion are 0.1-1.0 ms (3.3-30 μs). Activation energies in the 1.1-8.0 kcal/mol range are estimated. Future prospects include extension to the 2H relaxation limit, application to the 15N and 13C NMR nuclei, and accounting for collective motions and anisotropic media.

Original languageEnglish
Pages (from-to)2857-2868
Number of pages12
JournalJournal of Physical Chemistry B
Volume119
Issue number7
DOIs
StatePublished - 19 Feb 2015

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

Funding

FundersFunder number
Israel Science Foundation437/11
National Institute of General Medical SciencesP41GM103521

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