Superslow Backbone Protein Dynamics as Studied by 1D Solid-State MAS Exchange NMR Spectroscopy

Hydration dependence of backbone and side chain polylysine dynamics: A 13C solid‐state NMR and IR spectroscopy study

“…Both experiments report a side chain motion with a correlation time of the order of 10 Ϫ9 s. Selective measurements of 13 C relaxation times and NOEs for different carbons 16 have shown that similar to the solid state, the side chain motion becomes less restricted as the distance from the main chain increases.…”

“…The determination of 1 H and 13 C spin-lattice relaxation times in the laboratory and rotating frames at various temperatures and resonance frequencies, 9 -12 combined with 1D solid-state magic angle spinning (MAS) exchange techniques, 13 may provide much more abundant, reliable, and exact information with less a priori assumptions. In the present work, we apply a wide range of NMR relaxation techniques to a detailed molecular dynamics study of a synthetic homopolypeptide poly-L-lysine (PL) in solid state.…”

“…In a standard natural abundance 13 C CPMAS spectrum, all five aliphatic carbons of this amino acid residue can be clearly resolved. This permits obtaining highly selective information on backbone and side chain motions without expensive isotope enrichment procedures and/or timeconsuming multidimensional NMR protocols.…”

“…The most comprehensive NMR study of PL dynamics in solid state up to now was described in an article by Swanson and Bryant 15 who measured linewidths, cross-polarization time constants, and T 1 and T 1 relaxation times for the different lines in the natural abundance 13 C CPMAS spectrum of PL at several hydration levels from 0 to 50%. From the comparison of these parameters for different carbons and different hydration levels, the authors drew the conclusion that the PL backbone in ␤-sheet conformation is considerably more rigid than side chains and that the side chain mobility increases as the hydration and/or distance from the main chain increases.…”

“…15, we apply natural abundance 13 C relaxometry for PL dynamic study. However, the range of experiments in the present work is much wider: we have measured temperature dependencies of spin-lattice relaxation times T 1 at two resonance frequencies, off-resonance relaxation times T 1 in the tilted rotating frame at two spin-lock fields and proton decoupled on-resonance relaxation times T 1 at low spin-lock field.…”