Collins Christiane, Zhou Xinfeng, Wang Rong, Barth Marita C, Jiang Tao, Coderre Jeffrey A, Dedon Peter C
Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Radiat Res. 2005 Jun;163(6):654-62. doi: 10.1667/rr3344.
Emerging evidence points to the importance of deoxyribose oxidation in the toxicity of oxidative DNA damage, including the formation of protein-DNA crosslinks and base adducts. With the goal of understanding the differences in deoxyribose oxidation chemistry known to occur with different oxidants, we have compared the formation of one product of 3'-oxidation of deoxyribose in DNA, 3'-phosphoglycolaldehyde (PGA) residues, in isolated DNA and cells exposed to ionizing radiations. A recently developed gas chromatography/negative chemical ionization mass spectrometry method was used to quantify PGA residues in purified DNA and in human TK6 lymphoblastoid cells exposed to gamma radiation (60Co) and alpha particles (241Am). The level of PGA residues was then correlated with the total quantity of deoxyribose oxidation determined by plasmid topoisomer analysis. Alpha-particle irradiation (0-100 Gy) of purified DNA in 50 mM potassium phosphate (pH 7.4) produced a linear dose response of 0.13 PGA residues per 10(6) nucleotides per gray. When normalized to an estimate of the total number of deoxyribose oxidation events (2.0 per 10(6) nucleotides per gray), PGA formation occurred in 7% (+/-0.5) of deoxyribose oxidation events produced by alpha-particle radiation. In contrast, the efficiency of PGA formation in gamma-irradiated DNA was found to be 1% (+/-0.02), which indicates a shift in the chemistry of deoxyribose oxidation, possibly as a result of the different track structures of the two types of ionizing radiation. Studies with gamma radiation were extended to TK6 cells, in which it was observed that gamma radiation produced a linear dose response of 0.0019 PGA residues per 10(6) nucleotides per gray. This is consistent with an approximately 1000-fold quenching effect in cells, similar to the results of other published studies of oxidative DNA damage in vivo.
新出现的证据表明，脱氧核糖氧化在氧化性DNA损伤的毒性中具有重要作用，包括蛋白质-DNA交联和碱基加合物的形成。为了了解已知不同氧化剂引发的脱氧核糖氧化化学差异，我们比较了在暴露于电离辐射的分离DNA和细胞中，DNA中脱氧核糖3'-氧化的一种产物3'-磷酸乙醇醛（PGA）残基的形成情况。采用最近开发的气相色谱/负化学电离质谱法，对纯化DNA以及暴露于γ射线（60Co）和α粒子（241Am）的人TK6淋巴母细胞中的PGA残基进行定量。然后将PGA残基水平与通过质粒拓扑异构分析确定的脱氧核糖氧化总量相关联。在50 mM磷酸钾（pH 7.4）中对纯化DNA进行α粒子辐照（0 - 100 Gy），产生了每格雷每10(6)个核苷酸0.13个PGA残基的线性剂量响应。当将其归一化为脱氧核糖氧化事件总数的估计值（每格雷每10(6)个核苷酸2.0个）时，PGA形成发生在α粒子辐射产生的脱氧核糖氧化事件的7%（±0.5）中。相比之下，发现γ射线辐照DNA中PGA形成的效率为1%（±0.02），这表明脱氧核糖氧化化学发生了变化，可能是由于这两种电离辐射的不同径迹结构所致。对γ射线的研究扩展到了TK6细胞，在其中观察到γ射线产生了每格雷每10(6)个核苷酸0.0019个PGA残基的线性剂量响应。这与细胞中约1000倍的淬灭效应一致，类似于其他已发表的体内氧化性DNA损伤研究结果。
