NMR studies of large protein systems.

Over the recent years, there has been increased interest in applying NMR spectroscopy for the characterization of proteins and protein complexes of large molecular weight. The combination of multidimensional NMR, novel pulse sequences allowing for the selection of slowly relaxing coherence pathways, and the development of a range of labeling techniques has enabled high-resolution NMR analyses of supramolecular systems of even megadalton size. Here, we describe how NMR can be used to obtain structural information in large systems by using as an example the recent structure determination of SecA ATPase (204 kDa) in complex with a signal peptide.