https://doi.org/10.1007/s100510051043
Stretching DNA: Role of electrostatic interactions
Institute of Physical Science and Technology, University of Maryland, College Park,
Maryland 2074, USA
Received:
13
October
1998
Revised:
9
June
1999
Published online: 13 August 2012
The effect of electrostatic interactions on the stretching of DNA is
investigated using a simple worm like chain model. In the
limit of small force there are large conformational
fluctuations which are treated using a self-consistent variational approach.
For small values of the external force f, we find
the extension scales as 
where
rD is the Debye screening length.
In the limit of large force the electrostatic effects can be accounted for within
the semiflexible chain model of DNA by assuming that only small excursions from
rod-like conformations are possible. In this regime the extension
approaches the contour length as 
where f is the magnitude of
the external force. The theory is used to analyze
experiments that have measured the extension of double-stranded DNA subject to
tension at various salt concentrations. The theory reproduces nearly
quantitatively the elastic
response of DNA at small and large values of f and for all concentration of
the monovalent counterions. The limitations of the theory are also pointed out.
PACS: 36.20.-r – Macromolecules and polymer molecules / 61.25.Hq – Macromolecular and polymer solutions; polymer melts; swelling / 87.15.By – Structure and bonding
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999
