DNA radiation damage: insights from ab initio molecular dynamics simulations

DIPC Seminars

Jorge Kohanoff. Queen's University Belfast, United Kingdom.
Donostia International Physics Center
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DNA radiation damage: insights from ab initio molecular dynamics simulations Learning how ionising radiation interacts with DNA at the molecular level is important to assess the risks posed by various radiation sources, e.g. UV, X-rays, or ions, and to improve radiotherapeutic treatments of cancer. Radiation can interact directly with DNA, or indirectly by ionising the surrounding medium, thus generating a large number of electrons and leaving behind as many radicals. Both, electrons and radicals can interact with DNA. For a long time the responsibility for DNA damage was ascribed to attack by radicals. In 2000, a seminal work by L. Sanche's group in Sherbrooke (Canada) showed that electrons can also cause damage to DNA by a mechanism named dissociative electron attachment. The electron is captured in a resonant electronic state forming a transient negative ion, that decays by transferring electronic energy to vibrations of specific bonds that can eventually break. If these correspond to DNA strand breaks, they constitute the first step towards unrecoverable damage and cell death. In this seminar I will present our efforts in trying to understand the role of low-energy (excess) electrons at the molecular level by means of computer simulation of DNA fragments solvated in water and in the presence of amino acids. We are particularly interested in assessing the role of the fluctuating environment, as most of the existing calculations and experiments are carried out under rather artificial conditions, like gas phase molecules or clusters, or frozen samples, but rarely under the conditions prevalent in the cell. I will also present some preliminary results of the interaction between radio- and chemotherapy in DNA intercalated with Cisplatin.