Flying DNA Cation Radicals in the Gas Phase: Generation and Action Spectroscopy of Canonical and Noncanonical Nucleobase Forms
Flying DNA Cation Radicals in the Gas Phase: Generation and Action Spectroscopy of Canonical and Noncanonical Nucleobase Forms
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气相中飞行的 DNA 阳离子自由基：规范和非规范核碱基形式的生成和作用光谱
DOI：
10.1021/acs.jpcb.1c03674
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Tureček, František
中科院分区：
文献类型：
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作者：
Tureček, František
由于阳离子自由基生成、离子光谱和反应性研究的新方法的发展，与电离核酸相关的阳离子自由基气相化学最近取得了重大进展。基于过渡金属络合物分子内电子转移的氧化方法已经被用来产生核碱基和核苷阳离子自由基。在气相离子-离子反应中，依靠分子间电子转移的还原方法已经被用来生成一些二核苷酸和四核苷酸阳离子自由基，以及电荷标记的核苷自由基。通过红外光谱、紫外可见光谱、从头算和密度泛函理论计算，对生成的阳离子自由基进行了研究，给出了优化的结构、谐波频率和激发态分析。这导致了稳定的非正则核碱阳离子自由基的发现，这些自由基具有不寻常的电子性质和极低的离子-电子复合能。对阳离子自由基寡核苷酸和Watson-Crick核苷对的分子内质子转移反应进行了实验研究，并从理论上阐明了其机理。虽然目前氧化法的应用范围仅限于碱基和易氧化的鸟苷，但还原法可以扩大规模以产生包括双链DNA在内的大分子寡核苷酸阳离子自由基。讨论了DNA阳离子自由基的实验和计算方法中的挑战。
Gas-phase chemistry of cation radicals related to ionized nucleic acids has enjoyed significant recent progress thanks to the development of new methods for cation radical generation, ion spectroscopy, and reactivity studies. Oxidative methods based on intramolecular electron transfer in transition-metal complexes have been used to generate nucleobase and nucleoside cation radicals. Reductive methods relying on intermolecular electron transfer in gas-phase ion–ion reactions have been utilized to generate a number of di- and tetranucleotide cation radicals, as well as charge-tagged nucleoside radicals. The generated cation radicals have been studied by infrared and UV–visible action spectroscopy and ab initio and density functional theory calculations, providing optimized structures, harmonic frequencies, and excited-state analysis. This has led to the discovery of stable noncanonical nucleobase cation radicals of unusual electronic properties and extremely low ion–electron recombination energies. Intramolecular proton-transfer reactions in cation radical oligonucleotides and Watson–Crick nucleoside pairs have been studied experimentally, and their mechanisms have been elucidated by theory. Whereas the range of applications of the oxidative methods is currently limited to nucleobases and readily oxidizable guanosine, the reductive methods can be scaled up to generate large oligonucleotide cation radicals including double-strand DNA. Challenges in the experimental and computational approach to DNA cation radicals are discussed.