Molecular disorder structural order parameter

Structure of thermotropic liquid crystals is rather well understood. There are three main structural types nematic, cholesteric, and smectic. In nematic liquid crystals molecules are aligned approximately in the same direction, but positionally molecules are disordered. An axis of preferable molecular orientation is called a director. More precisely, the director is defined as a unit vector n(r) that is parallel to the molecular orientation at the point r. If we use the long axis of the molecules as a reference and denote it as k, the microscopic scalar order parameter 5 is defined [16,17] as follow ... 

We have also begun to structurally characterize fibrillar states of a-synuclein (140 residues) and of the K19 domain of protein tau. Both systems are involved in possibly related neuro-degenerative diseases.Preliminary results of two- and three-dimensional correlation spectroscopy, as outlined above, reveal that many of the NMR detectable resonances exhibit narrow or line widths, consistent with the occurrence of well-ordered domains in both proteins. On the other hand, other segments of the considered proteins cannot readily be detected suggesting that they may display static or dynamic disorder under the experimental conditions considered. While the effect of molecular dynamics of NMR relaxation parameters has been studied in the context of solution- or solid-state NMR for a long time, recent progress in the study of uniformly labelled proteins by MAS NMR has created novel means by which to study dynamics of entire polypeptide sequences using 2D methods. For example, Bockmann and Emsley have... 

---