Friday, 8 April 11:00am – 12:00pm

This seminar will be delivered in Chemistry Lecture Theatre 4 and Online Zoom Please email chemistry.researchsupport@sydney.edu.au for zoom link and password.

Speaker: Dr Andrew Wildes; Institut Laue-Langevin, France

Host: Prof. Chris Ling

Title: Melting and denaturation of oriented DNA studied with neutron scattering

Abstract: The base-pair bonds in double-stranded DNA will spontaneously break as temperature is increased, ultimately resulting in a complete dissociation into two single-stranded molecules, in a process known as the melting transition.  The melting transition has long been studied to probe the interactions within DNA, the influence of the base-pair sequence on DNA unwinding, and the effect of the solvent on DNA stability.  The transition is a highly dynamic process, and efforts have been made to develop theory to model it.  The Peyrard-Bishop-Dauxois (PBD) model [1] is of particular interest as it presents a Hamiltonian for the dynamics, offering a tantalising possibility that a more general expression could be developed to describe this highly important molecule [2].

The melting transition has typically been studied using bulk techniques such as calorimetry and circular dichroism.  However, these methods do not give direct information on spatial correlations between denaturing regions of the DNA which is important information for a complete understanding of the dynamics of the transition.  Neutron and synchrotron scattering methods do probe spatial correlations, and DNA can be prepared in forms where scattering experiments are particularly suited.  In this talk I will discuss our studies using scattering to understand the structure and dynamics of the melting transition of DNA in a variety of configurational forms and aqueous environments, and the subsequent analysis of the data using the PBD model [3].

[1] M. Peyrard and A. R. Bishop, Phys. Rev. Lett. 62, 2755 (1989); Dauxois et al., Phys. Rev. E 47, R44 (1993).

[2] J. Maddox, Nature 339 (1989) 577

[3] A. R. Wildes et al., Phys. Rev. Lett. 106 (2011) 048101; J. Valle-Orero et al., New J. Phys. 16 (2014) 113017; A. Gonzalez et al., (2021) https://doi.org/10.1002/bip.23422