DNP enhanced biomolecular NMR spectroscopy at high magnetic field and fast magic-angle spinning
Résumé
Dynamic Nuclear Polarization (DNP) is an effective approach to alleviate the inherently low sensitivity of solid-state NMR under magic angle spinning (MAS), opening new possibilities for the investigation of the structure and dynamics of large-sized biomolecular assemblies. The signal enhancement comes, however, at the expense of a substantial signal broadening,associated with the necessity to perform experiments at cryogenic temperatures (at about 100 K), and with the presence of paramagnetic radicals.
In this presentation, we will show that high quality DNP- enhanced NMR spectra of the Acinetobacterphage 205 (AP205) nucleocapsid can be obtained by combining high magnetic field (800 MHz) and fast MAS (40kHz). In particular, we will show that these experimental conditions yield enhanced resolution, with observed carbon-13 NMR linewidths mainly
governed by the inhomogeneous broadening. The increased refocused coherence lifetime allows the acquisition of scalar-based experiments, which in combination with dipolar spectra, enables the detection and assignment of long-range contacts, not observed at room temperature. The performance and limitations of current DNP polarizing agents with respect to high magnetic field and fast MAS will be finally discussed.