Dimensions of a plectonemic DNA supercoil under fairly general perturbations

Theo Odijk, Job Ubbink

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


A dimensional relation between the superhelical pitch angle and the superhelical radius is derived for plectonemic DNA. A uniform classical Hamiltonian is extracted from the free energy of the supercoil. The DNA superhelix may be perturbed by a variety of sources, but this does not alter the theoretical argumentation. Semiclassical arguments are presented for the validity of the analysis although one may simply appeal to establishing a classical superhelical "trajectory" experimentally. The theory is in good agreement with the microscopic determination of the plectonemic dimensions of closed circular DNA by T.C. Boles et al. (J. Mol. Biol. 213 (1990) 931).

Original languageEnglish (US)
Pages (from-to)61-66
Number of pages6
JournalPhysica A: Statistical Mechanics and its Applications
Issue number1-2
StatePublished - Apr 1 1998
Externally publishedYes


  • DNA
  • Plectonemic helix
  • Semiclassical approximations
  • Supercoiling
  • Topology

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