One-electron oxidation of ds(5'-GGG-3') and ds(5'-G(8OG)G-3') and the nature of hole distribution: a density functional theory (DFT) study.
One-electron oxidation of ds(5'-GGG-3') and ds(5'-G(8OG)G-3') and the nature of hole distribution: a density functional theory (DFT) study.
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ds(5-GGG-3) 和 ds(5-G(8OG)G-3) 的单电子氧化和空穴分布的性质：密度泛函理论 (DFT) 研究。
DOI：
10.1039/c9cp06244k
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Close,DavidM
中科院分区：
文献类型：
--
作者：
Kumar,Anil;Adhikary,Amitava;Sevilla,MichaelD;Close,DavidM
在DNA中辐射诱导的电荷转移过程中特别感兴趣的是电离和随后的弛豫后立即空穴定位的程度。为了解决这个问题，我们考虑了含有鸟嘌呤（G）和8-氧代鸟嘌呤（8 OG）的双链寡聚体，即，ds（5′-GGG-3′）和ds（5′-G8OGG-3′）。使用DFT，我们计算了各种性质，即，垂直和绝热电离势，自旋密度分布在氧化堆栈，溶剂和溶质重组能和单电子氧化电位（E0）在水相中。对-GGG-阳离子自由基垂直态的计算表明，自旋主要（67%）在中间G上。然而，在弛豫到绝热-GGG-阳离子自由基时，自旋局域化（96%）在5′-G上，如实验中所观察到的。空穴定位在中间G和3′-G上的能量分别比5′-G高0.5 kcal mol−1和0.4 kcal mol−1。在-G8 OGG-阳离子自由基中，自旋在垂直态和绝热态下都只局限于8 OG上。计算的垂直电离势的-GGG-和-G8 OGG-堆栈被发现是低于在DNA中的单个G的垂直电离势。计算的-GGG-和-G8 OGG-堆叠的E0值分别为1.15和0.90 V，由于堆叠效应，其显著低于其单体的相应实验E0值（分别为1.49和1.18 V）。在这些氧化堆栈中观察到自组织氧化到HOMO能级切换。因此，我们的计算预测，在DNA的本地双氧化将形成三重态的双自由基状态，这是特别重要的高LET辐射。
Of particular interest in radiation-induced charge transfer processes in DNA is the extent of hole localization immediately after ionization and subsequent relaxation. To address this, we considered double stranded oligomers containing guanine (G) and 8-oxoguanine (8OG), i.e., ds(5′-GGG-3′) and ds(5′-G8OGG-3′) in B-DNA conformation. Using DFT, we calculated a variety of properties, viz., vertical and adiabatic ionization potentials, spin density distributions in oxidized stacks, solvent and solute reorganization energies and one-electron oxidation potential (E0) in the aqueous phase. Calculations for the vertical state of the -GGG- cation radical showed that the spin was found mainly (67%) on the middle G. However, upon relaxation to the adiabatic -GGG- cation radical, the spin localized (96%) on the 5′-G, as observed in experiments. Hole localizations on the middle G and 3′-G were higher in energy by 0.5 kcal mol−1 and 0.4 kcal mol−1, respectively, than that of 5′-G. In the -G8OGG- cation radical, the spin localized only on the 8OG in both vertical and adiabatic states. The calculated vertical ionization potentials of -GGG- and -G8OGG- stacks were found to be lower than that of the vertical ionization potential of a single G in DNA. The calculated E0 values of -GGG- and -G8OGG- stacks are 1.15 and 0.90 V, respectively, which owing to stacking effects are substantially lower than the corresponding experimental E0 values of their monomers (1.49 and 1.18 V, respectively). SOMO to HOMO level switching is observed in these oxidized stacks. Consequently, our calculations predict that local double oxidations in DNA will form triplet diradical states, which are especially significant for high LET radiations.
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影响因子：
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作者：
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通讯作者：
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