High-Temperature Dynamic Nuclear Polarization Enhanced Magic-Angle-Spinning NMR

Dynamic nuclear polarization (DNP) transfers electron spin-polarization to nuclear spins in close proximity, increasing sensitivity by two-to-three orders of magnitude. This enables nuclear magnetic resonance (NMR) experiments on samples with low concentrations of analyte. The requirement of using cryogenic temperatures in DNP-enhanced solid-state NMR (ssNMR) experiments may impair the resolution and hence limit its broad application to biological systems. In this work, we introduce a "High-Temperature DNP" approach, which aims at increasing spectral resolution by performing experiments at temperatures of around 180 K instead of similar to 100 K. By utilizing the extraordinary enhancements obtained on deuterated proteins, still sufficiently large DNP enhancements of 11-18 are obtained for proton and carbon, respectively. We recorded high sensitivity 2D C-13-C-13 spectra in similar to 9 min with higher resolution than at 100 K, which has similar resolution to the one obtained at room temperature for some favorable residues.