Media for studies of partially aligned states.

Measurement of residual dipolar couplings for proteins in nuclear magnetic resonance (NMR) requires a degree of molecular alignment. This may be achieved through the use of liquid crystals or compressed hydrated gels. Several media have been described in the literature, and this chapter describes five of the most commonly used systems. For two of these systems, bicelles and filamentous bacteriophage, the media can be purchased in a form ready for experiments. The remainder must be made by the investigator, yet they are generally straightforward to synthesize in the laboratory. Poly(ethylene glycol)/alcohol mixtures and Helfrich phases are made by simply mixing the ingredients in the correct manner, and strained gels use techniques familiar to all molecular biologists.