Induction of strand breaks in polyribonucleotides and DNA by the sulphate radical anion: role of electron loss centres as precursors of strand breakage.
Induction of strand breaks in polyribonucleotides and DNA by the sulphate radical anion: role of electron loss centres as precursors of strand breakage.
复制标题
硫酸根阴离子诱导多核糖核苷酸和 DNA 链断裂：电子损失中心作为链断裂前体的作用。
DOI：
10.1080/09553009314551061
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发表时间：
1993
影响因子：
2.6
通讯作者：
P. O'Neill
中科院分区：
文献类型：
--
作者：
P. Wolf;G. D. Jones;L. P. Candeias;P. O'Neill
用时间分辨激光光散射(TRLS)测定，硫酸根阴离子SO4-与聚核苷酸聚U和聚C在pH 7.5的脱氧水溶液中的相互作用导致断链(SB)，其效率分别为57%和23%。大多数Sb是在70微秒内产生的，这是检测系统的上升时间。氧通过与Sb的自由基前体物相互作用来抑制SO4对聚U和聚C中Sb的诱导。相反，SO4.-与聚A和单链DNA的相互作用不会导致显著的链断裂(或=5%的效率)。从光学研究来看，聚A和聚G与SO4.-自由基的相互作用主要产生相应的一个电子被氧化的碱性自由基。对于聚C和聚U，提出了SO4·-主要通过与碱基的加成反应生成C(5)和C(6)-硫酸盐自由基加合物与氧反应。这些碱加合物随后通过H原子抽提与糖-磷酸部分相互作用，生成C(2)‘糖自由基，其速率常数在1.3x10(5)S-1范围内。有人认为，C(2)‘糖自由基在70微秒内导致链断裂，与其转变为C(1)-糖自由基涉及碱基释放的竞争。对SO4.-与双链DNA相互作用的光学研究表明，DNA中产生的主要自由基物种是鸟嘌呤的单电子氧化自由基，这与DNA中的正电荷迁移是一致的。由于SO4.-诱导单链DNA中Sb的效率较低，因此得出结论：单电子氧化的鸟嘌呤自由基不能有效地诱导DNA链断裂。
The interaction of the sulphate radical anion, SO4.-, with the polyribonucleotides, poly U and poly C, in deaerated, aqueous solutions at pH 7.5 results in strand breakage (sb) with efficiencies of 57 and 23%, respectively, determined by time resolved laser light scattering (TRLS). Most sb are produced within 70 microseconds, the risetime of the detection system. Oxygen inhibits the induction of sb in poly U and poly C by SO4.- through its interaction with a radical precursor to sb. In contrast, the interaction of SO4.- with poly A and single stranded DNA does not lead to significant strand breakage (< or = 5% efficiency). From optical studies, the interaction of poly A and poly G with SO4.- radicals yields predominantly the corresponding one electron oxidized base radicals. With poly C and poly U, it is proposed that the SO4.- radical interacts predominantly by addition to the base moiety to produce the C(5)-yl and C(6)-yl sulphate radical adducts which react with oxygen. These base adducts subsequently interact with the sugar-phosphate moiety by H-atom abstraction to yield C(2)' sugar radicals with rate constants in the range 1.3-1.7 x 10(5) s-1. It is proposed that the C(2)' sugar radical leads to strand breakage within 70 microseconds, in competition with its transformation into the C(1)'-sugar radical involving base release. From optical studies on the interaction of SO4.- with double stranded DNA, it is suggested that the predominant radical species produced in DNA is the one-electron oxidized radical of guanine, consistent with positive charge migration in DNA. Since the efficiency of SO4.- to induce sb in single stranded DNA is low, it is concluded that the one-electron oxidized guanine radical does not effectively induce strand breakage in DNA.