DNA不断暴露于各种有害因素,which,一方面,可以迫使不良过程,如老化,致癌和诱变,而另一方面,可以加速进化变化。在所有经典核苷中,2'-脱氧鸟苷(dG)表现出最低的电离电势,使其特别容易发生单电子氧化过程。最丰富的核碱基损伤类型由7,8-二氢-8-氧代-2'-脱氧鸟苷(OXOdG)组成,氧化电位比标准dG低0.56V。所有这些都导致了OXOdG,作为孤立的病变,被认为是基因组中自由基阳离子的汇。在本文中,在聚集的DNA损伤(CDL)的背景下,对OXOGC碱基对的电子特性进行了比较分析.它基于先前的DFT研究,这些研究是在未平衡和平衡的冷凝相中的理论M06-2x/6-31++G**水平下进行的。此处呈现的比较分析的结果揭示了以下内容:(A)OXOG4C2的电离电势在很大程度上不受第二损伤的影响。(B)发现正电荷和自旋主要在OXOG4C2部分上。(C)在Marcus倒置区域发现了电子-空穴转移A3T3→G4C2和G4C2-A5T1,并且对紧邻的第二个DNA损伤具有抵抗力。因此,可以合理地假设OXOGC成为自由基阳离子通过双螺旋迁移的汇,无论CDL结构中是否存在其他2'-脱氧鸟苷病变。
DNA is continuously exposed to a variety of harmful factors, which, on the one hand, can force undesirable processes such as ageing, carcinogenesis and mutagenesis, while on the other hand, can accelerate evolutionary changes. Of all the canonical nucleosides, 2\'-deoxyguanosine (dG) exhibits the lowest ionization potential, making it particularly prone to the one-electron oxidizing process. The most abundant type of nucleobase damage is constituted by 7,8-dihydro-8-oxo-2\'-deoxyguanosine (OXOdG), with an oxidation potential that is 0.56 V lower than that of canonical dG. All this has led to OXOdG, as an isolated lesion, being perceived as a sink for radical cations in the genome. In this paper, a comparative analysis of the electronic properties of an OXOGC base pair within the context of a clustered DNA lesion (CDL) has been conducted. It is based on previous DFT studies that were carried out at the M06-2x/6-31++G** level of theory in non-equilibrated and equilibrated condensed phases. The results of the comparative analysis presented here reveal the following: (A) The ionization potentials of OXOG4C2 were largely unaffected by a second lesion. (B) The positive charge and spin were found predominantly on the OXOG4C2 moiety. (C) The electron-hole transfers A3T3→G4C2 and G4C2←A5T1 were found in the Marcus inverted region and were resistant to the presence of a second DNA lesion in close proximity. It can therefore be reasonably postulated that OXOGC becomes the sink for a radical cation migrating through the double helix, irrespective of the presence of other 2\'-deoxyguanosine lesions in the CDL structure.