Deprotonation Kinetics of 1-Methylguanine After One-Electron Oxidation
文献类型：期刊论文
| 作者 | Wu Lidan; Jie Jialong; Liu Kunhui; Su Hongmei |
| 刊名 | acta chimica sinica
 |
| 出版日期 | 2014-11-15 |
| 卷号 | 72期号:11页码:1182-1186 |
| 关键词 | 1-methylguanine deprotonation one-electron oxidation rate constant activation energy barrier |
| 英文摘要 | among the four natural dna bases, guanine (g) is the most sensitive to oxidation due to its lowest oxidation potential. when g base is oxidized to guanine cation radical (g(+center dot)), it will deprotonate from both the imino proton n-1-h and the amino proton n-2-h. according to the pka values for n-1-h and n-2-h deprotonation, the main deprotonation site in g base is n-1-h which would interfere with the n-2-h deprotonation, making the kinetics of n-2-h deprotonation difficult to be measured. herein, the n-2-h deprotonation kinetics is investigated using 1-methylguanosine (mg), where n-1-h is substituted by methyl group to avoid the n-1-h deprotonation and n-9-h is substituted by ribose to ensure enough solubility of methylguanine in water, by nanosecond transient absorption (ns-ta) spectroscopy. by 355 nm photolysis of na2s2o8, the highly oxidizing radical so4-center dot is generated, which will oxidize mg to mg(+center dot) instantaneously. the time-resolved absorption spectra obtained for reaction of mg with so4-center dot exhibits transient absorptions for mg(n-2-h)(center dot) featured by absorption band at 600 nm, indicating that the mg(+center dot) deprotonation product is mg(n-2-h)(center dot) and the deprotonation site is therefore validated to be n-2-h. the mg concentration dependence of mg(n-2-h)(center dot) formation rate constant is assessed through changing the mg concentration from 0.25 mmol.l-1 to 5 mmol.l-1. the concentration dependence experiment reveals that the rate-limiting step to form mg(n-2-h)(center dot) is the bimolecular reaction of mg with so4-center dot when mg concentration is lower than 2 mmol.l-1 and the bimolecular reaction rate constant to form mg(+center dot) is (3.7 +/- 0.1)x10(9) l.mol(-1).s(-1); when mg concentration is above 2 mmol.l-1, the rate-limiting step to form mg(n-2-h)(center dot) is the first-order mg(+center dot) deprotonation and the n-2-h deprotonation rate constant is (7.1 +/- 0.2) x 10(6) s(-1). furthermore, the n-2-h deprotonation rate constant is measured at different temperatures varying from 278 k to 298 k. according to arrhenius equation, the activation energy barrier for the n-2-h deprotonation is determined to be 19.9 +/- 1.0 kj.mol(-1). these results can provide valuable kinetic information on the oxidative damage of dna. |
| WOS标题词 | science & technology ; physical sciences |
| 类目[WOS] | chemistry, multidisciplinary |
| 研究领域[WOS] | chemistry |
| 关键词[WOS] | guanine radical-cation ; aqueous-solution ; irradiated guanine ; hydroxyl radicals ; laser photolysis ; dna-damage ; base-pair ; guanosine ; repair ; equilibria |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000346121300010 |
| 公开日期 | 2016-05-09 |
| 源URL | [http://cas-ir.dicp.ac.cn/handle/321008/145699]  |
| 专题 | 大连化学物理研究所_中国科学院大连化学物理研究所 |
| 作者单位 | Chinese Acad Sci, Inst Chem, BNLMS, State Key Lab Mol React Dynam, Beijing 100190, Peoples R China |
| 推荐引用方式 GB/T 7714 | Wu Lidan,Jie Jialong,Liu Kunhui,et al. Deprotonation Kinetics of 1-Methylguanine After One-Electron Oxidation[J]. acta chimica sinica,2014,72(11):1182-1186. |
| APA | Wu Lidan,Jie Jialong,Liu Kunhui,&Su Hongmei.(2014).Deprotonation Kinetics of 1-Methylguanine After One-Electron Oxidation.acta chimica sinica,72(11),1182-1186. |
| MLA | Wu Lidan,et al."Deprotonation Kinetics of 1-Methylguanine After One-Electron Oxidation".acta chimica sinica 72.11(2014):1182-1186. |
入库方式： OAI收割
来源：大连化学物理研究所
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