Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides†,Photochemical & Photobiological Sciences

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Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides†
Photochemical & Photobiological Sciences ( IF 2.7 ) Pub Date : 2018-03-23 00:00:00 , DOI: 10.1039/c8pp00040a
Lara Martínez-Fernández _{1,

2,

3,

4,

5} , Roberto Improta _{1,

2,

3,

4,

5}

Affiliation

The excited states involved in the main photodimerization paths in TpdC and dCpT are mapped by PCM/TD-M052X calculations, considering different dinucleotide conformers. As for TT steps, a cyclobutane pyrimidine dimer (CPD) is formed on the PES of the lowest energy exciton, delocalized over two stacked pyrimidines; 6–4 pyrimidine–pyrimidone (64-PP) adduct's formation involves instead a 5′-ter → 3′-ter charge transfer state. For dCpT, 64-PP dimerization occurs via a two-step reaction, which proceeds through an oxetane intermediate. For TpdC, instead, the final 64-PP product is obtained in a single step and it is as stable as the CPD photoproduct, explaining the relatively large yield of 64-PP found experimentally for TC steps in DNA.

中文翻译：

对DNA光化学的序列依赖性：TpdC和dCpT二核苷酸中光二聚途径的计算研究†

考虑到不同的二核苷酸构象体，通过PCM / TD-M052X计算来映射TpdC和dCpT中主要的光二聚化路径所涉及的激发态。对于TT步骤，在能量最低的PES上形成环丁烷嘧啶二聚体（CPD），并在两个堆叠的嘧啶上进行离域。6-4嘧啶-嘧啶酮（64-PP）加合物的形成涉及5'-ter→3'-ter的电荷转移态。对于dCpT，64-PP二聚是通过两步反应进行的，该反应通过氧杂环丁烷中间体进行。相反，对于TpdC，最终的64-PP产物可在一个步骤中获得，并且与CPD光产物一样稳定，这说明了在实验中针对DNA中的TC步骤发现的64-PP的产率相对较高。

更新日期：2018-03-23

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