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首页> 外文期刊>Biochemistry >MECHANISM OF SITE-SELECTIVE DNA NICKING BY THE HYDRODIOXYL (PERHYDROXYL) RADICAL
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MECHANISM OF SITE-SELECTIVE DNA NICKING BY THE HYDRODIOXYL (PERHYDROXYL) RADICAL

机译：羟基自由基的选择性DNA克隆机理

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摘要

In previous studies, the ability of the hydrodioxyl (perhydroxyl) radical [HOO., the conjugate acid of superoxide (O-2(.-))] to ''nick'' DNA under biomimetic conditions was demonstrated, and a sequence selectivity was observed. A background level of nonspecific nicking also was noted. This paper provides support for 5'-hydrogen atom abstraction from the deoxyribose ring as the initial event in the sequence-selective nicking by O-2(.-)/HOO.. Two experiments support the proposed mechanism. First, using a defined sequence 5'-P-32-labeled restriction fragment as the DNA substrate, only free (unalkylated) 3'-phosphate is produced at the site of nicking, Second, using poly (dA). poly (T) as the substrate, furfural is formed in the reaction from deoxyribose ring breakdown. Both results are consistent with 5'-hydrogen atom abstraction for initiation of the site-selective nicking. Hydrogen atom abstraction at other sites of the deoxyribose ring and/or base oxidation and loss followed by strand scission likely are responsible for the nonspecific nicking. The 5'-abstraction mechanism contrasts to those elicited by other O-2-derived and metal-associated oxidants, which may provide a biomarker for the reactivity of HOO. in vivo.
机译：在以前的研究中，证明了在仿生条件下氢二氧基（过羟基）基团[HOO。，超氧化物的共轭酸（O-2（.-））]对“缺口” DNA的能力，并且其序列选择性为观测到的。还指出了非特异性刻痕的背景水平。本文为脱氧核糖环上5'-氢原子的提取提供了支持，这是O-2（.-）/ HOO在序列选择性刻痕中的初始事件。两个实验支持了所提出的机制。首先，使用定义的序列5'-P-32标记的限制性片段作为DNA底物，在刻痕部位仅产生游离的（未烷基化的）3'-磷酸，其次，使用聚（dA）。以聚（T）为底物，在脱氧核糖环分解反应中形成糠醛。两种结果均与5'-氢原子提取起始位点选择性切口一致。脱氧核糖环其他位点的氢原子提取和/或碱基的氧化和丢失，然后断裂，可能是造成非特异性切口的原因。 5'提取机理与其他O-2-衍生的和金属相关的氧化剂引发的机理相反，后者可能为HOO的反应性提供生物标记。体内。

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