Su, Y., L. Andreas, and R.G. Griffin, Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and H Detection. Annu Rev Biochem, 2015.
Magic angle spinning (MAS) NMR studies of amyloid and membrane proteins and large macromolecular complexes are an important new approach to structural biology. However, the applicability of these experiments, which are based on 13C- and 15N-detected spectra, would be enhanced if the sensitivity were improved. Here we discuss two advances that address this problem: high-frequency dynamic nuclear polarization (DNP) and 1H-detected MAS techniques. DNP is a sensitivity enhancement technique that transfers the high polarization of exogenous unpaired electrons to nuclear spins via microwave irradiation of electron-nuclear transitions. DNP boosts NMR signal intensities by factors of 102 to 103, thereby overcoming NMR's inherent low sensitivity. Alternatively, it permits structural investigations at the nanomolar scale. In addition, 1H detection is feasible primarily because of the development of MAS rotors that spin at frequencies of 40 to 60 kHz or higher and the preparation of extensively 2H-labeled proteins. Expected final online publication date for the Annual Review of Biochemistry Volume 84 is June 02, 2015. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.