Sébastien Neukirch
Institut Jean le Rond d'Alembert
Centre National de la Recherche Scientifique
Université Pierre et Marie Curie
Paris, France

tel: +33 1 44 27 72 61
fax : +33 1 44 27 52 59
e-mail: sebastien.neukirch (-atat-) upmc.fr

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Writhe formulas and antipodal points in plectonemic DNA configurations

Sébastien Neukirch and E. L. Starostin

Physical Review E, 78 041912 (2008)

Selected for the November 1, 2008 issue of the Virtual Journal of Biological Physics Research (VJBIO)

Figure 2 was selected for the PRE Kaleidoscope (Images of October 2008)

Abstract : The linking and writhing numbers are key quantities when characterizing the structure of a piece of supercoiled DNA. Defined as double integrals over the shape of the double-helix, these numbers are not always straightforward to compute, though a simplified formula was established in a theorem by Fuller (1978). We examine the range of applicability of this widely-used simplified formula, and show that it cannot be employed for plectonemic DNA. We show that inapplicability is due to a hypothesis of Fuller theorem that is not met. The hypothesis seems to have been overlooked in many works.

PACS numbers : 87.10.-e, 87.14.gk, 02.40.-k, 87.15.-v

download the pre-print version : PDF

download the article : PDF