Torsional fluctuations in columnar DNA assemblies

D. J. Lee, A. Wynveen

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


In columnar assemblies of helical bio-molecules the azimuthal degrees of freedom, i.e. rotations about the long axes of molecules, may be important in determining the structure of the assemblies, especially when the interaction energy between neighbouring molecules explicitly depends on their relative azimuthal orientations. For DNA this leads to a rich variety of mesophases for columnar assemblies, each categorized by a specific azimuthal ordering. In a preceding paper (Wynveen et al 2005 Eur. Phys. J. E 16 303) a statistical mechanical theory was developed for the assemblies of torsionally rigid molecules in order to determine how thermal fluctuations influence the structure of these mesophases. Here we extend this theory by including torsional fluctuations of the molecules, where a DNA molecule may twist about its long axis at the cost of torsional elastic energy. Comparing this with the previous study, we find that inclusion of torsional fluctuations further increases the density at which the transition between the hexagonal structure and the predicted rhombic phase occurs and reduces the level of distortion in the rhombic phase. As x-ray diffraction may probe the 2D lattice structure of such assemblies and provide information concerning the underlying interaction between molecules, we have also calculated correlation functions for the azimuthal ordering which are manifest in x-ray scattering intensity profiles.

Original languageEnglish (US)
Pages (from-to)787-823
Number of pages37
JournalJournal of Physics Condensed Matter
Issue number3
StatePublished - Jan 25 2006


Dive into the research topics of 'Torsional fluctuations in columnar DNA assemblies'. Together they form a unique fingerprint.

Cite this