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Quantum Tunnelling Effect in DNA Base Pair Mutation.

Godbeer, Adam. (2014) Quantum Tunnelling Effect in DNA Base Pair Mutation. Doctoral thesis, University of Surrey (United Kingdom)..

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The influence of quantum tunnelling on double hydrogen transfers within DNA base pairs is investigated by solving the time-dependent Schrodinger equation (TDSE) for a one-dimensional double well potential, whilst accounting for environment coupling. The energies of the canonical (standard, amino-keto) and tautomeric (non-standard, imino-enol) charge-neutral forms of the adenine-thymine base pair (A-T and A*-T*, respectively) are calculated using density functional theory. These compare favourably to results in existing literature. The reaction pathway is also calculated using a transition state search to provide the barrier height and shape, and these are combined to create the potential using a polynomial fit. It is found that tunnelling is very unlikely to be a significant mechanism for the creation of adenine-thymine tautomers within DNA, with the anti-Zeno effect from environment coupling only being able to boost the tunnelling probability at any given time to ~2 x 10-9. This is barely increased when varying several parameters, such as barrier height, potential asymmetry, and mass (kinetic isotope effect). In addition, the general effect on a quantum system by its surrounding environment is explored. A novel comparison between two distinct methods of environment coupling - dissipation (via the addition of a Lindblad term to the master equation) and von Neumann measurements - is performed. This is done using a simpler model of benzoic acid dimer, where it is shown that the two methods describe the same physical process of decoherence and can be thought of as equivalent until the link between them breaks down at high temperatures and measurement frequencies.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Godbeer, Adam.
Date : 2014
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2014.
Depositing User : EPrints Services
Date Deposited : 24 Apr 2020 15:26
Last Modified : 24 Apr 2020 15:26

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