Bechinger, Burkhard. “DNP Solid-State NMR of Biological Membranes” 7 (2018): 10.
While solid-state NMR/DNP has become a well-established technique to significantly increase the signals of molecules embedded in homogeneous glassy matrices, the enhancement factors observed in heterogeneous and/or matrix-free samples lag somewhat behind. The possible reasons for such differences, present limitations, and future prospects of solid-state NMR/DNP are discussed in the context of membrane protein investigations. Membrane polypeptides and lipids are studied by MAS as well as oriented sample solid-state NMR approaches. Notably, even the more modest DNP signal enhancements obtained in such samples augment the signal intensities by 1–2 orders of magnitude, thus opening up new territory in structural biology by allowing the detection of new conformers, so far invisible intermediate states, or the acquisition of smaller quantities of membrane-associated polypeptides in much less time. New sample preparation protocols, dedicated instrumental hardware, and specifically designed biradicals have much improved the application of DNP to membranes using MAS and/or oriented solid-state NMR technologies.