光化学介导氧自由基对dna损伤机理分析-mechanism analysis of photochemical mediated oxygen free radical damage to dna.docxVIP

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光化学介导氧自由基对dna损伤机理分析-mechanism analysis of photochemical mediated oxygen free radical damage to dna.docx

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光化学介导氧自由基对dna损伤机理分析-mechanism analysis of photochemical mediated oxygen free radical damage to dna

三峡大学硕士学位论文三峡大学硕士学位论文 PAGE PAGE VIBiOBr 光化学反应剧烈，介导产生高浓度的?OH 和 O2?-，致使 DNA 氧化损伤程度严重；而紫外光辐照 BiOBr 介导产生?OH，DNA 氧化损伤是?OH 氧化历程。5. 引入抗氧化剂或氧自由基清除剂，如超氧化物歧化酶(Superoxide dismutase, SOD)，在 UV(?=200-275 nm)辐照纳米二氧化钛(TiO2)介导氧自由基体系，研究了 SOD 作为 DNA 损伤抑制剂提高 DNA 抗辐射及抗氧化能力的拮抗机理。结果表明，SOD 能清除光化学过程中产生的 O2?-并在一定 pH 范围内抑制 O2?-生成 H2O2，延迟其光化学反应历程，降低·OH 的浓度，抑制·OH 对 DNA 损伤作用。关键词：光化学氧自由基 DNA 损伤AbstractDeoxyribonucleic acid (DNA), called genetic particle, is the genetic material for almost all the living beings and can guide biological development and vital functions. Various factors in environment (endogenous metabolites, chemicals, drugs, ionizing radiation, sunlight, smoking, air pollution, etc.) cause desmolysis, breakage and damage of DNA double helix. Studies have shown that free radicals, involving the process of canceration and aging, are main factors causing DNA damage. Sunlight consists of ultraviolet (UV, ?400 nm), visible light (Vis, ?=400-780 nm) and infrared ray (IR, ?780 nm). Under UV (3.00-5.00 % of solar irradiation) irradiation, highly active oxidation species (hydroxyl radical (·OH), superoxide radical (O2?-), singlet oxygen (1O2), etc.) form. Therefore, the study of DNA damage by oxyradical mediated by photochemistry and mechanism are helpful for the understanding of life course. The main contents of this paper are as follows.Calf thymus DNA was used as the object to study the DNA damage by oxyradical.8-Hydroxy-2`-deoxyguanosine (8-OHdG) was used as the internal standard. Intermediate products were detected and analyzed by High Performance Liquid Chromatography (HPLC) and High Performance Liquid Chromatography/ Mass Spectrometry (HPLC-MS/MS). Electron Spin Resonance (ESR) and Spectrophotometry were employed to determine oxidation species and the concentration of H2O2, respectively. The mechanism of DNA damage was studied.Herring sperm DNA was used as the object to study the DNA damage by oxyradical excited by TiO2 under UV irradiation (?=200-275 nm). ESR and Spectrophotome