Photosensitization of thymine nucleobase by benzophenone through energy transfer, hydrogen abstraction and one-electron oxidation
Photosensitization of thymine nucleobase by benzophenone through energy transfer, hydrogen abstraction and one-electron oxidation
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DOI：
10.1016/s1011-1344(98)00142-0
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发表时间：
1998-07-31
影响因子：
5.4
通讯作者：
Cadet, J
中科院分区：
文献类型：
--
作者：
Delatour, T;Douki, T;Cadet, J
为了了解二苯甲酮介导的胸苷光敏化的机制，已与甲萘醌光敏化获得的结构的比较观察到的病变，以及它们各自的量。重点阐述了二苯甲酮介导的胸腺嘧啶和胸苷酰-（3' -> 5'）-胸腺嘧啶（TpT）光敏化的机理。这是通过对主要最终光产物的定量测量来实现的。通过比较甲萘醌介导的胸苷光敏化获得的数据，进一步了解的机制功能。在二苯甲酮和甲萘醌介导的胸苷光敏化中，通过气相色谱/质谱（GC/MS）分析鉴定并准确定量了5-（羟甲基）-2 '-脱氧尿苷（HMdUrd）、5-甲酰基-2'-脱氧尿苷（FordUrd）和5，6-二羟基-5，6-二氢胸苷（DOHdThd）的四种非对映异构体。发现在二苯甲酮介导的光敏化的情况下，[HMdUrd + FordUrd] / [DOHdThd]比甲萘醌高5倍。这强烈地表明二苯甲酮能够从胸腺嘧啶核碱基的甲基中提取氢。此外，DOHdThd的形成为胸腺嘧啶核碱基的额外氧化机制的发生提供了证据。在核苷模型上观察到的胸腺嘧啶碱基二聚化在TpT上定量。这提供了关于能量转移反应和电荷转移过程的相对效率的相关信息。(C)1998年Elsevier Science S.A. All rights reserved.
In order to understand the mechanism of benzophenone-mediated photosensitization of thymidine, a comparison of the structure of the observed lesions, as well as their respective amounts, has been made with those obtained by photosensitization with menadione. Emphasis is placed on the elucidation of the mechanisms of benzophenone-mediated photosensitization of the thymine moiety of thymidine and thymidylyl-(3' --> 5')-thymidine (TpT). This is achieved by the quantitative measurement of the main final photoproducts. Further insights into the mechanistic feature are gained by comparing the data obtained on menadione-mediated photosensitization of thymidine. In benzophenone-and menadione-mediated photosensitization of thymidine, 5-(hydroxymethyl)-2'-deoxyuridine (HMdUrd), 5-formyl-2'-deoxyuridine (FordUrd) and the four diastereoisomers of 5,6-dihydroxy-5,6-dihydrothymidine (DOHdThd) are identified and accurately quantified by gas chromatography/mass spectrometry (GC/MS) analysis. The ratio [HMdUrd + FordUrd] / [DOHdThd] is found to be five-fold higher in the case of the benzophenone-mediated photosensitization than in the menadione one. This is strongly indicative that benzophenone is able to abstract a hydrogen from the methyl group of thymine nucleobase. Moreover, the formation of DOHdThd provides evidence for the occurrence of an additional oxidative mechanism of the thymine nucleobase. The thymine base dimerization, observed on the nucleoside model, is quantified on TpT. This provides relevant information about the relative efficiency of the energy-transfer reaction and charge-transfer process. (C) 1998 Elsevier Science S.A. All rights reserved.