Beschreibung:
<jats:title>Abstract</jats:title><jats:p><jats:sup>15</jats:sup>N <jats:italic>R</jats:italic><jats:sub>1ρ</jats:sub> relaxation experiments in solid‐state NMR spectroscopy are sensitive to timescales and amplitudes of internal protein motions in the hundreds of nano‐ to microsecond time window, which is difficult to probe by solution‐state NMR spectroscopy. By using <jats:sup>15</jats:sup>N <jats:italic>R</jats:italic><jats:sub>1ρ</jats:sub> relaxation experiments, a simplified approach to detect low microsecond protein dynamics is described and residue‐specific correlation times are determined from the ratio of <jats:sup>15</jats:sup>N <jats:italic>R</jats:italic><jats:sub>1ρ</jats:sub> rate constants at different magic angle spinning frequencies. Microcrystalline ubiquitin exhibits small‐amplitude dynamics on a timescale of about 1 μs across the entire protein, and larger amplitude motions, also on the 1 μs timescale, for several sites, including the β<jats:sub>1</jats:sub>–β<jats:sub>2</jats:sub> turn and the N terminus of the α helix. According to the analysis, the microsecond protein backbone dynamics are of lower amplitude than that concluded in previous solid‐state NMR spectroscopy studies, but persist across the entire protein with a rather uniform timescale of 1 μs.</jats:p>