NMR-based structural biology enhanced by dynamic nuclear polarization at high magnetic field
Dynamic nuclear polarization (DNP) has become a powerful method to enhance spectroscopic sensitivity in the context of magnetic resonance imaging and nuclear magnetic resonance spectroscopy. We show that, compared to DNP at lower field (400 MHz/263 GHz), high field DNP (800 MHz/527 GHz) can significantly enhance spectral resolution and allows exploitation of the paramagnetic relaxation properties of DNP polarizing agents as direct structural probes under magic angle spinning conditions. Applied to a membrane-embedded K+ channel, this approach allowed us to refine the membrane-embedded channel structure and revealed conformational substates that are present during two different stages of the channel gating cycle. High-field DNP thus offers atomic insight into the role of molecular plasticity during the course of biomolecular function in a complex cellular environment.
KeywordsNMR Dynamic nuclear polarization Membrane Protein Solid-state NMR
Dynamic nuclear polarization
Magic angle spinning
Paramagnetic relaxation enhancement
Solid-state nuclear magnetic resonance
Magnetic resonance imaging
Proton-driven spin diffusion
We thank Mark Daniels for excellent technical support. This work was supported by NWO (grants 722.012.002 to MW and 700.11.344 and 700.58.102 to MB), DFG (Po137, 40-1 and 41-1) and NIH (NIH/NIGNS grant GM087519).