Some more information on encapsulated proteins, an approach that was shown recently to be a very interesting path for solution-state DNP by the same group.
Nucci, N.V., K.G. Valentine, and A.J. Wand, High-resolution NMR spectroscopy of encapsulated proteins dissolved in low-viscosity fluids. J Magn Reson, 2014. 241(0): p. 137-47.
High-resolution multi-dimensional solution NMR is unique as a biophysical and biochemical tool in its ability to examine both the structure and dynamics of macromolecules at atomic resolution. Conventional solution NMR approaches, however, are largely limited to examinations of relatively small (<25kDa) molecules, mostly due to the spectroscopic consequences of slow rotational diffusion. Encapsulation of macromolecules within the protective nanoscale aqueous interior of reverse micelles dissolved in low viscosity fluids has been developed as a means through which the ‘slow tumbling problem’ can be overcome. This approach has been successfully applied to diverse proteins and nucleic acids ranging up to 100kDa, considerably widening the range of biological macromolecules to which conventional solution NMR methodologies may be applied. Recent advances in methodology have significantly broadened the utility of this approach in structural biology and molecular biophysics.