Oxygen Dependent Purine Lesions in Double-Stranded Oligodeoxynucleotides: Kinetic and Computational Studies Highlight the Mechanism for 5′,8-Cyclopurine Formation

Chryssostomos Chatgilialoglu*, Leif A. Eriksson, Marios G. Krokidis, Annalisa Masi, Shudong Wang, Rubo Zhang

*此作品的通讯作者

科研成果: 期刊稿件文章同行评审

20 引用 (Scopus)

摘要

The reaction of HO radical with DNA is intensively studied both mechanistically and analytically for lesions formation. Several aspects related to the reaction paths of purine moieties with the formation of 5′,8-cyclopurines (cPu), 8-oxopurines (8-oxo-Pu), and their relationship are not well understood. In this study, we investigated the reaction of HO radical with a 21-mer double-stranded oligodeoxynucleotide (ds-ODNs) in γ-irradiated aqueous solutions under various oxygen concentrations and accurately quantified the six purine lesions (i.e., four cPu and two 8-oxo-Pu) by LC-MS/MS analysis using isotopomeric internal standards. In the absence of oxygen, 8-oxo-Pu lesions are only ∼4 times more than cPu lesions. By increasing oxygen concentration, the 8-oxo-Pu and the cPu gradually increase and decrease, respectively, reaching a gap of ∼130 times at 2.01 × 10-4 M of O2. Kinetic treatment of the data allows to estimate the C5′ radical competition between cyclization and oxygen trapping in ds-ODNs, and lastly the rate constants of the four cyclization steps. Tailored computational studies by means of dispersion-corrected DFT calculations were performed on the CGC and TAT in their double-strand models for each cPu diastereoisomer along with the complete reaction pathways of the cyclization steps. Our findings reveal unheralded reaction mechanisms that resolve the long-standing issues with C5′ radical cyclization in purine moieties of DNA sequences.

源语言英语
页(从-至)5825-5833
页数9
期刊Journal of the American Chemical Society
142
12
DOI
出版状态已出版 - 25 3月 2020

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