A compact high-speed mechanical sample shuttle for field-dependent high-resolution solution NMR

Analysis of NMR relaxation data has provided significant insight on molecular dynamic, leading to a more comprehensive understanding of macromolecular functions. However, traditional methodology allows relaxation measurements performed only at a few fixed high fields, thus severely restricting their potential for extracting more complete dynamic information. Here we report the design and performance of a compact high-speed servo-mechanical shuttle assembly adapted to a commercial 600 MHz high-field superconducting magnet. The assembly is capable of shuttling the sample in a regular NMR tube from the center of the magnet to the top (fringe field ∼0.01 T) in 100 ms with no loss of sensitivity other than that due to intrinsic relaxation. The shuttle device can be installed by a single experienced user in 30 min. Excellent 2D- ¹⁵N-HSQC spectra of (u- ¹³C, ¹⁵N)-ubiquitin with relaxation at low fields (3.77 T) and detection at 14.1 T were obtained to illustrate its utility in R ₁ measurements of macromolecules at low fields. Field-dependent ¹³C-R ₁ data of (3,3,3-d)-alanine at various field strengths were determined and analyzed to assess CSA and ¹H- ¹³C dipolar contributions to the carboxyl ¹³C-R ₁.