5,5-二甲基-1-吡咯啉N-氧化物（DMPO）自旋俘获无机自由基的理论和实验研究。1.二氧化碳自由基阴离子。,The Journal of Physical Chemistry A

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5,5-二甲基-1-吡咯啉N-氧化物（DMPO）自旋俘获无机自由基的理论和实验研究。1.二氧化碳自由基阴离子。
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2006 Dec 14 , DOI: 10.1021/jp064892m
Frederick A. Villamena ₁ , Edward J. Locigno ₁ , Antal Rockenbauer ₁ , Christopher M. Hadad ₁ , Jay L. Zweier ₁

Affiliation

已知二氧化碳自由基阴离子（CO2 *-）是通过各种化学和生化途径在体内产生的。电子顺磁共振（EPR）自旋阱与常用的自旋阱5,5-二甲基-1-吡咯啉N-氧化物（DMPO）已用于检测CO2 *-。使用密度泛函理论（DFT）在B3LYP / 6-31 ++ G ** // B3LYP / 6-31G *和B3LYP / 6-311 + G *浓度下，预测了向DMPO中添加CO2 *-的热力学。可极化连续体模型（PCM），用于模拟水的整体介电效应对计算出的高能学的影响。预测了向DMPO添加CO2 *-的三种可能的产物：（1）羧酸酯加合物，（2）吡咯啉醇和（3）DMPO-OH。实验上，在甲酸钠（NaHCO2）和DMPO的存在下，H2O2的UV光解产生了以C为中心的羧酸酯加合物的EPR光谱特征，并且与理论推导的超精细偶合常数（hfcc）一致。羧酸酯加合物的pKa经计算估计为6.4。据预测，向DMPO中添加CO2 *-的方式主要由自由基上的自旋（密度）族决定，而静电效应并不是形成持久加合物的主要因素。预测CO2 *-在水相中的热力学行为类似于巯基（* SH），表明在生物系统中CO2 *-的形成可能在细胞氧化损伤的引发中起重要作用。

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Theoretical and experimental studies of the spin trapping of inorganic radicals by 5,5-dimethyl-1-pyrroline N-oxide (DMPO). 1. Carbon dioxide radical anion.

The carbon dioxide radical anion (CO2*-) is known to be generated in vivo through various chemical and biochemical pathways. Electron paramagnetic resonance (EPR) spin trapping with the commonly used spin trap, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), has been employed in the detection of CO2*-. The thermodynamics of CO2*- addition to DMPO was predicted using density functional theory (DFT) at the B3LYP/6-31++G**//B3LYP/6-31G* and B3LYP/6-311+G* levels with the polarizable continuum model (PCM) to simulate the effect of the bulk dielectric effect of water on the calculated energetics. Three possible products of CO2*- addition to DMPO were predicted: (1) a carboxylate adduct, (2) pyrroline-alcohol and (3) DMPO-OH. Experimentally, UV photolysis of H2O2 in the presence of sodium formate (NaHCO2) and DMPO gave an EPR spectrum characteristic of a C-centered carboxylate adduct and is consistent with the theoretically derived hyperfine coupling constants (hfcc). The pKa of the carboxylate adduct was estimated computationally to be 6.4. The mode of CO2*- addition to DMPO is predicted to be governed predominantly by the spin (density) population on the radical, whereas electrostatic effects are not the dominant factor for the formation of the persistent adduct. The thermodynamic behavior of CO2*- in the aqueous phase is predicted to be similar to that of mercapto radical (*SH), indicating that formation of CO2*- in biological systems may have an important role in the initiation of oxidative damage in cells.

更新日期：2017-01-31

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