One-Electron Oxidation of Individual DNA Bases and DNA Base Stacks
One-Electron Oxidation of Individual DNA Bases and DNA Base Stacks
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DOI：
10.1021/jp906963f
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发表时间：
2010-02-04
影响因子：
2.9
通讯作者：
Close, David M.
中科院分区：
文献类型：
--
作者：
Close, David M.
在用DFT进行的计算中，嘌呤阳离子有在堆叠中的几个碱基上离域的趋势。已经尝试，看看是否可以使用DFT以外的方法来计算本地化的阳离子在堆叠的嘌呤，并与已知的实验结果计算超精细耦合。为了计算可靠的超精细耦合，有必要对自旋极化进行充分的描述，这意味着必须正确处理电子相关。UMP 2理论在估计自旋密度时由于高估了加倍修正而被证明是不可靠的。因此，人们尝试用二次组态相互作用（UQCISD）方法来处理电子关联。对单个DNA碱基的计算表明，用UQCISD方法计算超精细耦合是可能的，与实验结果吻合良好。然而，这些UQCISD计算比DFT计算更耗时。然后将计算扩展到两个堆叠的鸟嘌呤碱基。用UMP2或UQCISD理论的初步计算表明，两个堆叠的鸟嘌呤导致一个阳离子局部化的油，一个鸟嘌呤碱基。
In calculations performed with DFT there is a tendency of the purine cation to be delocalized over several bases in the stack. Attempts have been made to see if methods other than DFT can be used to calculate localized cations in stacks of purines, and to relate the calculated hyperfine Couplings with known experimental results. To calculate reliable hyperfine couplings it is necessary to have an adequate description of spin polarization which means that electron correlation must be treated properly. UMP2 theory has been shown to be unreliable in estimating spin densities due to overestimates of the doubles correction. Therefore attempts have been made to use quadratic configuration interaction (UQCISD) methods to treat electron correlation. Calculations on the individual DNA bases are presented to show that with UQCISD methods it is possible to calculate hyperfine couplings in good agreement with the experimental results. However these UQCISD calculations are far more time-consuming than DFT calculations. Calculations are then extended to two stacked guanine bases. Preliminary Calculations with UMP2 or UQCISD theory oil two stacked guanines lead to a cation localized oil a single guanine base.