Chapter 6: NMR Experiments for Measuring RDCs in Biomolecules Check Access

The measurement of residual dipolar couplings (RDCs) in biomolecules requires accurate measurement of scalar couplings. Because RDCs are used to interpret protein structure and motions, high precision is required, and many NMR experiments have been developed to measure several major classes of couplings accurately. A broad range of experiments are available, each with particular considerations, such as the appropriate macromolecular size or the desired perdeuteration level. In this chapter, we describe the general concepts involved in RDC measurement, targeting researchers wishing to add RDCs to their experimental toolbox. After considering the experimental uncertainty in RDCs, we present two major classes of experiments: direct measurements based on peak positions and quantitative J measurements based on peak intensities. We discuss the strengths and weaknesses of each approach and highlight recent examples where they have been fruitfully used. For more advanced spectroscopists, we include a table of commonly used experiments, indexed by coupling type. Finally, we close by discussing future directions for RDC measurement and the utility of non-uniform sampling approaches.