The geometrical origin of the strain-twist coupling in double helices

    Research output: Contribution to journalJournal articleResearchpeer-review

    406 Downloads (Pure)


    A simple geometrical explanation for the counterintuitive phenomenon when twist leads to extension in double helices is presented. The coupling between strain and twist is investigated using a tubular description. It is shown that the relation between strain and rotation is universal and depends only on the pitch angle. For pitch angles below 39.4◦ strain leads to further winding, while for larger pitch angles strain leads to unwinding. The zero-twist structure, with a pitch angle of 39.4◦, is at the unique point between winding and unwinding and independent of the mechanical properties of the double helix. The existence of zero-twist structures, i.e. structures that display neither winding, nor unwinding under strain is discussed. Close-packed double helices are shown to extend rather than shorten when twisted. Numerical estimates of this elongation upon winding are given for DNA, chromatin, and RNA.
    Original languageEnglish
    Article number012108
    JournalA I P Advances
    Number of pages7
    Publication statusPublished - 2011


    • DNA
    • Proteins
    • Molecular biophysics
    • Molecular configurations
    • Biomechanics

    Fingerprint Dive into the research topics of 'The geometrical origin of the strain-twist coupling in double helices'. Together they form a unique fingerprint.

    Cite this