Magnetic tweezers, a powerful single-molecule manipulation technique, can be adapted for the direct measurements of the twist (using a configuration called freely-orbiting magnetic tweezers) and torque (using a configuration termed magnetic torque tweezers) in biological macromolecules. Guidelines for performing such measurements are given, including applications to the study of DNA and associated nucleo-protein filaments.
Lipfert, J., Lee, M., Ordu, O., Kerssemakers, J. W. J., Dekker, N. H. Magnetic Tweezers for the Measurement of Twist and Torque. J. Vis. Exp. (87), e51503, doi:10.3791/51503 (2014).