Do Solvated Electrons (eaq‿/sup>) Reduce DNA Bases? A Gaussian 4 and Density Functional Theory- Molecular Dynamics Study

详细信息    查看全文

• 作者：Anil Kumar ; Amitava Adhikary ; Lance Shamoun ; Michael D. Sevilla
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：March 10, 2016
• 年：2016
• 卷：120
• 期：9
• 页码：2115-2123
• 全文大小：419K
• ISSN：1520-5207

文摘

The solvated electron (e_aq^–) is a primary intermediate after an ionization event that produces reductive DNA damage. Accurate standard redox potentials (E^o) of nucleobases and of e_aq^– determine the extent of reaction of e_aq^– with nucleobases. In this work, E^o values of e_aq^– and of nucleobases have been calculated employing the accurate ab initio Gaussian 4 theory including the polarizable continuum model (PCM). The Gaussian 4-calculated E^o of e_aq^– (−2.86 V) is in excellent agreement with the experimental one (−2.87 V). The Gaussian 4-calculated E^o of nucleobases in dimethylformamide (DMF) lie in the range (−2.36 V to −2.86 V); they are in reasonable agreement with the experimental E^o in DMF and have a mean unsigned error (MUE) = 0.22 V. However, inclusion of specific water molecules reduces this error significantly (MUE = 0.07). With the use of a model of e_aq^–-nucleobase complex with six water molecules, the reaction of e_aq^– with the adjacent nucleobase is investigated using approximate ab initio molecular dynamics (MD) simulations including PCM. Our MD simulations show that e_aq^– transfers to uracil, thymine, cytosine, and adenine, within 10 to 120 fs and e_aq^– reacts with guanine only when a water molecule forms a hydrogen bond to O6 of guanine which stabilizes the anion radical.