In this paper, we seek to compare the internal dynamics of a small globular protein, SH3
domain from α-spectrin, in solution and in a crystalline state. The comparison involves side-
chain methyl 13C R 1 relaxation rates that are highly sensitive to local dynamics in the
vicinity of the methyl site. To conduct the relaxation measurements, protein samples have
been prepared using specially labeled α-ketoisovalerate precursors, resulting in selective
incorporation of the 1H− 13C spin pair in one or both methyl groups of the valine and …

Rapid advances in solid-state MAS NMR made it possible to probe protein dynamics on a
per-residue basis, similar to solution experiments. In this work we compare methyl 2H
relaxation rates measured in the solid and liquid samples of α-spectrin SH3 domain. The
solution data are treated using a model-free approach to separate the contributions from the
overall molecular tumbling and fast internal motion. The latter part forms the basis for
comparison with the solid-state data. Although the accuracy of solid-state measurements is …