Physics applied to DNA: thermodynamics and the melting transition

Date & time

1–2pm 20 February 2014


Building 136 Lecture Theatre


Dr Andrew Wildes


 Gavin Perri

The description by Watson and Crick of the double helix structure of DNA
[1] led to a fundamental postulate that ³form is function² for biological
molecules, meaning that the properties of the molecule are due only to
its structure. It is now increasingly clear that a description of
function must take into account the dynamics of the molecules.

The dynamics of DNA are often quantified through physical, thermodynamic
parameters such as its entropy and free energy, however these are still
only understood from a largely phenomenological standpoint.  These
quantities can be investigated using physical science models and
computational tools.  Attempts have been made to develop Hamiltonians to
describe the "melting transition", whereby  the two strands of the double
helix will spontaneously break as temperature is increased, and to
calculate the presence and dispersion of phonons that can exist in this
rather stiff molecule.  Information on spatial correlations within the
molecule is necessary to test the predictions of theory.  Neutron and
synchrotron scattering techniques are excellent tools for these types of

In this talk I will discuss some of the recent work we have performed,
using neutron and synchrotron radiation to study the dynamics [2] and
melting transition [3] of DNA.  The data are compared quantitatively to
the predictions from theory, and to data from complementary techniques
such as calorimetry and UV absorption spectroscopy.  The results show the
potential for the application of physical science methods to this
important molecule.

[1] J. D. Watson and F. H. C. Crick, Nature 171 (1953) 737
[2] L. van Eijck et al., Phys. Rev. Lett. 107 (2011) 088102.
[3] A. R. Wildes et al., Phys. Rev. Lett. 106 (2011) 048101; A. R. Wildes
et al., Phys. Rev. E 83 (2011) 061923

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