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遗传信息的完整性不断受氧化基因的威胁,7,8-二氢-8-氧鸟嘌呤(8-oxo-G)是氧化DNA损伤最常见的产物.氧化碱基会引起基因突变、癌变及衰老等.应用量子化学方法分析得出:鸟嘌呤(G)被氧化为8-oxo-G后,其电荷分布、氢键的供体和受体位点的数目和位置随之改变,N7和O6原子所带的电荷变得更负,使得它们作为氢键供体的能力增强.从而G被误认为其他碱基,与正常碱基形成多种氢键复合物.可将8-oxo-G划分为3个作用位点与正常碱基相互作用.与正常的单体相比,碱基对中形成氢键的受体原子上所带电荷平均变负0.05e,占原电荷的8%;供体H原子所带电荷平均变正0.02e,占原电荷的4%.1位点与正常碱基作用形成的氢键复合物更稳定,2位点和3位点性质相似,水溶剂使碱基对的结合能力减弱,其中与C作用形成氢键复合物的结合能减弱程度最大,且使碱基对结合能力的次序改变.在8-oxo-G导致的GC→TA突变中,亲核反应位点从G所在链转到A(C)所在链,影响酶对碱基的识别,从而产生基因突变.
The integrity of genetic information is continually threatened by oxidative genes, which are the most common products of oxidative DNA damage, and oxidative bases cause mutations, carcinogenesis and Aging, etc. The results of quantum chemical analysis showed that the number and location of the donor and acceptor sites of the charge distribution, hydrogen bond and the position of guanine (G) oxidized to 8-oxo- O6 atoms become more negative charge, making them as a hydrogen bond donor enhances the ability to G was mistaken for other bases, with the normal base to form a variety of hydrogen bond complexes can be 8-oxo-G Divided into three interaction sites with normal bases.Compared with the normal monomer, the base pairs on the formation of hydrogen bond acceptor atoms on the average charge minus 0.05e, accounting for 8% of the original charge; The charge of donor H atom is anomaly 0.02e, accounting for 4% of the original charge. The hydrogen bond complex formed by site 1 and normal base is more stable, and the properties of site 2 and 3 are similar. The binding ability of base pairs was weakened, in which the binding energy to form hydrogen bonding complex with C function was attenuated to the greatest extent, and the order of base binding ability was changed.In the case of 8-oxo-G GC → TA mutation, a nucleophilic reaction sites where G from chain to chain, where A (C), the influence on base recognition enzyme, thereby producing gene mutations.