Related Experiment Video
Updated: Jul 6, 2026

Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
Dipolar couplings in multiple alignments suggest alpha helical motion in ubiquitin
Jens Meiler1, Wolfgang Peti, Christian Griesinger
1Max Planck Insitute for Biophysical Chemistry, Göttingen, Germany.
Abstract:
Recently, residual dipolar couplings (RDCs) of backbone N-HN vectors measured in 11 different alignment media were analyzed with respect to structure and dynamics in a model-free way in terms of generalized order parameters and motional anisotropies. The anisotropies in the central alpha-helix were found to be strikingly uniformly distributed. In this communication, these parameters are further interpreted in terms of physically feasible cooperative reorientational motion of the helix with respect to the core of the protein. The RDCs are compatible with a model in which all N-HN vectors of the alpha-helix of ubiquitin exhibit correlated anisotropic excursions with amplitudes of 21 degrees and 12 degrees along two orthogonal directions x' ' and y' ' of a coordinate system C' ', if z' ' represents the helix axis. Such motion contradicts neither NOE data nor molecular force-field calculations.
Related Concept Videos
The Pauli Exclusion Principle
Polarity of the Cytoskeleton
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
¹H NMR Signal Multiplicity: Splitting Patterns
Coplanar Forces
Two Force Member

