Solid-state NMR on larger biomolecules

In the last years, remarkable progress has been made to probe molecular structure of biological systems using Magic Angle Spinning solid-state NMR (ssNMR). Prominent examples relate to research areas that have remained challenging to classical structural biology methods such as membrane proteins1,2 and protein fibrils (see, e.g., Ref. 3,4,5). In addition, ssNMR continues to contribute to a structural understanding of basic biological processes including enzyme catalysis or photosynthesis and is capable of studying far more complicated heterogeneous biomolecular systems such as bacterial cell walls6 or inclusion bodies7,8. Clearly, these advancements would have been impossible without methodological and instrumental progress in the field of ssNMR and the pioneering work of Griffin, Opella, Cross, Torchia and others in the field of biomolecular ssNMR. Yet, a decade ago, it was still unclear whether one would be able to obtain sequential assignments of larger proteins, not to mention the determination of their 3D structures from ssNMR data. Since then, ssNMR progress has been substantial and improvements in the field of solutionstate NMR continue to cross fertilize and speed up developments in solid-state NMR. Finally, the revolutionary developments in biochemistry and molecular biology in combination with isotope-labelling, and in more general sense, the ability to design biomolecular sample preparations for ssNMR studies has played a critical role. With further increasing molecular size, for example relating to proteins comprising several hundred amino acids, new challenges and opportunities lay ahead of us.