Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland.
J Phys Chem Lett. 2021 Oct 7;12(39):9463-9469. doi: 10.1021/acs.jpclett.1c02678. Epub 2021 Sep 24.
A better understanding of the mechanism of oxidative DNA damage requires obtaining a molecular level description of nucleotides in various charge states. Herein, we report a systematic photoelectron spectroscopy and theoretical investigation of the electronic and geometric structures of four doubly deprotonated 2'-deoxynucleoside 5'-monophosphate dianions, the smallest quintessential DNA building block. These dianions are intrinsically stable with their adiabatic/vertical detachment energies (ADE/VDE) ranging from 0.85/1.07 (A) and 1.05/1.30 (G) to 1.20/1.50 (C) and 1.80/2.10 eV (T). The repulsive Coulomb barrier against electron detachment is 2.0 eV for purines and 2.5 eV for pyrimidines. Dianions are deprotonated at the phosphate group and the amino group of a nucleobase. The π-type HOMO orbital resides on the nucleobase moiety for each dianion. This spatial distribution of HOMO suggests that the most loosely bound electron is detached along the direction perpendicular to the nucleobase. When combined with the previous results, this work makes complete the depiction of basic building blocks of DNA at the molecular level.
要更好地理解氧化 DNA 损伤的机制，就需要从分子水平上描述各种电荷状态下的核苷酸。在此，我们报告了对四个双去质子化 2'-脱氧核苷 5'-单磷酸二阴离子（最小的典型 DNA 构建基块）的光电电子能谱和理论研究的系统研究。这些二阴离子具有内在的稳定性，其绝热/垂直离解能（ADE/VDE）范围为 0.85/1.07（A）和 1.05/1.30（G）至 1.20/1.50（C）和 1.80/2.10 eV（T）。电子脱离的排斥库仑势垒对于嘌呤为 2.0 eV，对于嘧啶为 2.5 eV。二阴离子在磷酸基团和碱基的氨基处去质子化。每个二阴离子的 π 型 HOMO 轨道位于碱基部分。HOMO 的这种空间分布表明，最松散结合的电子沿垂直于碱基的方向脱离。当与以前的结果结合时，这项工作完整地描绘了 DNA 的基本构建块在分子水平上的结构。
