scholarly journals Rücktitelbild: The Triplet Hydroxyl Radical Complex of Phosphorus Monoxide (Angew. Chem. 49/2020)

2020 ◽  
Vol 132 (49) ◽  
pp. 22452-22452
Author(s):  
Xianxu Chu ◽  
Weiyu Qian ◽  
Bo Lu ◽  
Lina Wang ◽  
Jie Qin ◽  
...  
2003 ◽  
Vol 118 (17) ◽  
pp. 7797-7802 ◽  
Author(s):  
Anders Engdahl ◽  
Gunnar Karlström ◽  
Bengt Nelander

2020 ◽  
Vol 59 (49) ◽  
pp. 21949-21953
Author(s):  
Xianxu Chu ◽  
Weiyu Qian ◽  
Bo Lu ◽  
Lina Wang ◽  
Jie Qin ◽  
...  

2020 ◽  
Vol 142 (5) ◽  
pp. 2175-2179 ◽  
Author(s):  
Changyun Chen ◽  
Bo Lu ◽  
Xiaofang Zhao ◽  
Weiyu Qian ◽  
Jie Liu ◽  
...  

2020 ◽  
Vol 132 (49) ◽  
pp. 22133-22137
Author(s):  
Xianxu Chu ◽  
Weiyu Qian ◽  
Bo Lu ◽  
Lina Wang ◽  
Jie Qin ◽  
...  

2020 ◽  
Vol 59 (49) ◽  
pp. 22268-22268
Author(s):  
Xianxu Chu ◽  
Weiyu Qian ◽  
Bo Lu ◽  
Lina Wang ◽  
Jie Qin ◽  
...  

2004 ◽  
Vol 71 ◽  
pp. 97-106 ◽  
Author(s):  
Mark Burkitt ◽  
Clare Jones ◽  
Andrew Lawrence ◽  
Peter Wardman

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.


2018 ◽  
Author(s):  
Danilo Carmona ◽  
David Contreras ◽  
Oscar A. Douglas-Gallardo ◽  
Stefan Vogt-Geisse ◽  
Pablo Jaque ◽  
...  

The Fenton reaction plays a central role in many chemical and biological processes and has various applications as e.g. water remediation. The reaction consists of the iron-catalyzed homolytic cleavage of the oxygen-oxygen bond in the hydrogen peroxide molecule and the reduction of the hydroxyl radical. Here, we study these two elementary steps with high-level ab-initio calculations at the complete basis set limit and address the performance of different DFT methods following a specific classification based on the Jacob´s ladder in combination with various Pople's basis sets. Ab-initio calculations at the complete basis set limit are in agreement to experimental reference data and identified a significant contribution of the electron correlation energy to the bond dissociation energy (BDE) of the oxygen-oxygen bond in hydrogen peroxide and the electron affinity (EA) of the hydroxyl radical. The studied DFT methods were able to reproduce the ab-initio reference values, although no functional was particularly better for both reactions. The inclusion of HF exchange in the DFT functionals lead in most cases to larger deviations, which might be related to the poor description of the two reactions by the HF method. Considering the computational cost, DFT methods provide better BDE and EA values than HF and post--HF methods with an almost MP2 or CCSD level of accuracy. However, no systematic general prediction of the error based on the employed functional could be established and no systematic improvement with increasing the size in the Pople's basis set was found, although for BDE values certain systematic basis set dependence was observed. Moreover, the quality of the hydrogen peroxide, hydroxyl radical and hydroxyl anion structures obtained from these functionals was compared to experimental reference data. In general, bond lengths were well reproduced and the error in the angles were between one and two degrees with some systematic trend with the basis sets. From our results we conclude that DFT methods present a computationally less expensive alternative to describe the two elementary steps of the Fenton reaction. However, choice of approximated functionals and basis sets must be carefully done and the provided benchmark allows a systematic validation of the electronic structure method to be employed


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