1) DNP-Enhanced Experiments on Large Biological Systems
Dynamic Nuclear Polarization (DNP) experiments at 263 GHz/ 400 MHz provide a large gain in sensitivity and dramatic reduction in signal averaging time. This enhanced sensitivity enables researchers to study samples that otherwise would have been inaccessible to NMR such as certain membrane proteins or samples which are available only in very limited amounts or dilute concentration. A range of samples have been successfully enhanced on the new 263 GHz Bruker DNP spectrometer including small peptides, soluble proteins, membrane proteins, and large biological complexes. The DNP samples are prepared by adding a polarizing agent (such as e.g. TOTAPOL biradical to a shared solvent or alternatively by utilizing a native radical on the sample of interest. The samples are measured under MAS while at low temperatures, typically 100–120 K. Unmodified NMR experiments are performed while benefitting from continuously DNP-enhanced signal intensity through CW microwave irradiation.
2) DNP-Enhanced CPMAS of 13C-Proline
DNP-Enhanced CPMAS of 13C-Proline in Glycerol/Water with 20 mM TOTAPOL:25 μl sample, 1.5 mg U-13C-15N Proline, 8 kHz MAS, CPMAS with Spinal 64 decoupling, 110 k sample temperature, 8 seconds acquisition time for both microwaves on and off spectra
3) DNP-enhanced proton driven spin diffusion 13C-13C correlation experiment
DNP-enhanced proton driven spin diffusion 13C-13C correlation experiment on Barnase ribosome nascent chain complex with 10 mM TOTAPOL (nascent chain 13C labelled). 13 kHz MAS at 110 K. Experiment time: 17 hours. Sample courtesy of Hartmut Oschkinat, Leibnizinstitut fuer Molekulare Pharmakologie.