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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Medium-dependent interactions of quinones with cytosine and cytidine: a laser flash photolysis study with magnetic field effect.
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Medium-dependent interactions of quinones with cytosine and cytidine: a laser flash photolysis study with magnetic field effect.

机译：醌与胞嘧啶和胞苷的介质依赖性相互作用：具有磁场效应的激光闪光光解研究。

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摘要

Laser flash photolysis and an external magnetic field have been used for the study of the interaction of two quinone molecules, namely, 9,10-anthraquinone (AQ) and 2-methyl 1,4-naphthoquinone (or menadione, MQ) with a DNA base, cytosine (C) and its nucleoside cytidine (dC) in two media, a homogeneous one composed of acetonitrile/water (ACN/H(2)O, 9:1, v/v) and a SDS micellar heterogeneous one. We have applied an external magnetic field for the proper identification of the transients formed during the interactions in micellar media. Cytosine exhibits electron transfer (ET) followed by hydrogen abstraction (HA) while dC reveals a reduced ET compared to C, with both quinones in organic homogeneous medium (ACN/H(2)O). Due to a higher electron affinity, AQ supports more faciler ET than MQ with dC in ACN/H(2)O but observations in SDS have been just the reverse. In SDS, ET from dC is completely quenched and a dominant HA is all that could be discerned. This work reveals two main findings: first, a drop in ET on addition of a ribose unit to C, which has been attributed to a role of keto-enol tautomerism in inducing ET from electron-rich nucleus and second, the effect of medium in controlling reaction mechanism by favoring HA with AQ although it is intrinsically more prone towards ET.
机译：激光闪光光解法和外部磁场已用于研究两个醌分子，即9,10-蒽醌（AQ）和2-甲基1,4-萘醌（或甲萘醌，MQ）与DNA的相互作用碱，胞嘧啶（C）及其核苷胞苷（dC）在两种介质中，一种均质的介质由乙腈/水（ACN / H（2）O，9：1，v / v）和一种SDS胶束异质介质组成。我们已经应用了外部磁场来正确识别在胶束介质相互作用过程中形成的瞬变。胞嘧啶表现出电子转移（ET），然后是氢提取（HA），而dC则显示出与C相比，ET降低了，两种醌均在有机均质介质（ACN / H（2）O）中。由于较高的电子亲和力，AQ在ACN / H（2）O中比带有dC的MQ支持更容易的ET，但在SDS中的观察恰恰相反。在SDS中，来自dC的ET被完全淬灭，并且可以识别出主要的HA。这项工作揭示了两个主要发现：首先，向C中添加核糖单元后ET下降，这归因于酮-烯醇互变异构在富电子核诱导ET中的作用，其次是培养基中通过使用AQ支持HA来控制反应机制，尽管它本质上更倾向于ET。

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