阳离子对8-氧-7,8-二氢-2'-去氧鸟嘌呤核苷构型的影响

The Effects of Oxidation and Protonation on Conformation of 8-Oxo-2'-Deoxyguanosine

采用DFT理论的M05方法选用6-311++G(d,p)基组对8-氧-7,8-二氢-2'-去氧鸟嘌呤核苷的构型和糖苷键的稳定性进行了研究,考虑了阳离子对8-oxodG的构型和N—糖苷键稳定性的影响.研究结果表明,阳离子降低了N—糖苷键的稳定性,有利于N—糖苷键的断裂."异头碳影响"和由于在碱基引入正电荷而引起的缺电子影响促进N—糖苷键以异裂过程进行裂解,正电荷或金属离子的引入对促进N—糖苷键的断裂起着重要的作用,而且,异裂过程是糖苷键断裂的首选方式.

This work is an attempt to evaluate the effects of oxidation on the conformation and the N--glycosidic bond stability in 8- oxo-2＇-deoxyguanosine （8-oxodG） by using the density functional theory M05/6-311 ＋ ＋ G（ d, p） method. In all modified forms, the length of the Ng--cI＇ bond increases as compared to the neutral system 8-oxodG. It has been found that, for the systems studied, the ＂anomeric effect＂ and the electron-deficient effect for the presence of positive charge introduced in 8-oxoG favor significantly the heter- olytic dissociation, and the presence of the positive charge may play an important role in facilitating the N--glycosidic bond breaking. Furthermore, the heterolytic dissociation is favorable.