Enhanced Resolution and Coherence Lifetimes in the Solid-State NMR Spectroscopy of Perdeuterated Proteins under Ultrafast Magic-Angle Spinning
We investigate the combined effect of perdeuteration and fast magic-angle spinning on the resolution and sensitivity of proton-detected protein NMR spectra and on coherence lifetimes. With 60 kHz spinning of a microcrystalline alpha-spectrin SH3 sample at a field strength of 23 T, a regime is attained where there is no substantial difference in resolution between perdeuterated samples with 10 or 100% protons at the exchangeable sites. H-1 resolution is then limited by inhomogeneous contributions. Upon fast spinning, the most dramatic line narrowing effects are observed for residues in the loop or bend regions of the protein, probably due to the removal of destructive dynamics effects. This investigation paves the way for using samples with 100% protons at the exchangeable sites in structure determination protocols, since all backbone amide sites can now contribute to the signal.