Rotting by radicals – the role of cellobiose oxidoreductase?

2003 ◽  
Vol 31 (6) ◽  
pp. 1335-1336 ◽  
Author(s):  
M.G. Mason ◽  
P. Nicholls ◽  
M.T. Wilson
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radicals ◽  
Ferrous Iron ◽  
Functional Role ◽  
Fenton Chemistry ◽  
Lignocellulose Biodegradation

Cellobiose oxidoreductase is a flavocytochrome secreted by wood-rotting fungi. The structure and functional role of the enzyme are reviewed, and a mechanism through which the enzyme produces superoxide, ferrous iron and hydrogen peroxide is proposed. The reactions of hydroxyl radicals formed by Fenton chemistry are discussed in the context of lignocellulose biodegradation.

scholarly journals 2′,7′-dichlorofluorescin-based analysis of Fenton chemistry reveals auto-amplification of probe fluorescence and albumin as catalyst for the detection of hydrogen peroxide

2020 ◽  
Vol 477 (24) ◽  
pp. 4689-4710
Author(s):  
Teresa Gonzalez ◽  
Franck Peiretti ◽  
Catherine Defoort ◽  
Patrick Borel ◽  
Roland Govers
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Ferrous Iron ◽  
Fenton Reaction ◽  
Iron Chelation ◽  
Intact Cells ◽  
Free System ◽  
Fenton Chemistry ◽  
In Cells

Fluorophore 2′,7′-dichlorofluorescin (DCF) is the most frequently used probe for measuring oxidative stress in cells, but many aspects of DCF remain to be revealed. Here, DCF was used to study the Fenton reaction in detail, which confirmed that in a cell-free system, the hydroxyl radical was easily measured by DCF, accompanied by the consumption of H2O2 and the conversion of ferrous iron into ferric iron. DCF fluorescence was more specific for hydroxyl radicals than the measurement of thiobarbituric acid (TBA)-reactive 2-deoxy-D-ribose degradation products, which also detected H2O2. As expected, hydroxyl radical-induced DCF fluorescence was inhibited by iron chelation, anti-oxidants, and hydroxyl radical scavengers and enhanced by low concentrations of ascorbate. Remarkably, due to DCF fluorescence auto-amplification, Fenton reaction-induced DCF fluorescence steadily increased in time even when all ferrous iron was oxidized. Surprisingly, the addition of bovine serum albumin rendered DCF sensitive to H2O2 as well. Within cells, DCF appeared not to react directly with H2O2 but indirect via the formation of hydroxyl radicals, since H2O2-induced cellular DCF fluorescence was fully abolished by iron chelation and hydroxyl radical scavenging. Iron chelation in H2O2-stimulated cells in which DCF fluorescence was already increasing did not abrogate further increases in fluorescence, suggesting DCF fluorescence auto-amplification in cells. Collectively, these data demonstrate that DCF is a very useful probe to detect hydroxyl radicals and hydrogen peroxide and to study Fenton chemistry, both in test tubes as well as in intact cells, and that fluorescence auto-amplification is an intrinsic property of DCF.

scholarly journals Thimerosal-Derived Ethylmercury Is a Mitochondrial Toxin in Human Astrocytes: Possible Role of Fenton Chemistry in the Oxidation and Breakage of mtDNA

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Martyn A. Sharpe ◽  
Andrew D. Livingston ◽  
David S. Baskin
Keyword(s):  
Hydrogen Peroxide ◽  
Caspase 3 ◽  
Permeability Transition ◽  
Fold Increase ◽  
Hydrogen Peroxide Production ◽  
Fenton Chemistry ◽  
Human Astrocytes ◽  
Mitochondrial Toxin ◽  
Normal Human

Thimerosal generates ethylmercury in aqueous solution and is widely used as preservative. We have investigated the toxicology of Thimerosal in normal human astrocytes, paying particular attention to mitochondrial function and the generation of specific oxidants. We find that ethylmercury not only inhibits mitochondrial respiration leading to a drop in the steady state membrane potential, but also concurrent with these phenomena increases the formation of superoxide, hydrogen peroxide, and Fenton/Haber-Weiss generated hydroxyl radical. These oxidants increase the levels of cellular aldehyde/ketones. Additionally, we find a five-fold increase in the levels of oxidant damaged mitochondrial DNA bases and increases in the levels of mtDNA nicks and blunt-ended breaks. Highly damaged mitochondria are characterized by having very low membrane potentials, increased superoxide/hydrogen peroxide production, and extensively damaged mtDNA and proteins. These mitochondria appear to have undergone a permeability transition, an observation supported by the five-fold increase in Caspase-3 activity observed after Thimerosal treatment.

Role of Hydroxyl Radicals inEscherzchza ColzKilling Induced by Hydrogen Peroxide

1989 ◽  
Vol 6 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Giorgio Brandi ◽  
Flaminio Cattabeni ◽  
Amedeo Albano ◽  
Orazio Cantoni
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radicals

Use of an Improved Chemiluminescence Assay for Non-Intrusive Measurement of Hydroxyl Radicals in a Biomimetic Pulp Bleaching Model System

Holzforschung ◽  
1999 ◽  
Vol 53 (2) ◽  
pp. 181-187 ◽  
Author(s):  
C. C. Walker ◽  
R. J. Dinus ◽  
T. J. McDonough ◽  
K.-E. L. Eriksson
Keyword(s):  
Hydrogen Peroxide ◽  
Aqueous Solutions ◽  
Hydroxyl Radicals ◽  
Model System ◽  
Pulp Bleaching ◽  
Assay Sensitivity ◽  
Chemiluminescence Assay ◽  
Naturally Occurring ◽  
Excellent Tool

Summary A chemiluminescence assay was used to measure the production of hydroxyl radicals (·OH) in aqueous solutions of hydrogen peroxide and iron-containing catalysts. Preliminary experiments evaluating assay sensitivity revealed that one of the required reagents, phthalhydrazide (PtH), interfered with the studied reactions. In addition, undesirable degradation of the chemiluminescent form of PtH was observed. By removing PtH from reaction solutions and modifying the published procedures, a successful non-intrusive method for measurement of ·OH was obtained. The modified assay was used to compare the rate of ·OH generation in solutions of H2O2, either FeSO4 or Fe-EDTA and a substrate, lignosulfonate. This “biomimetic” pulp bleaching system is meant to simulate naturally occurring biological reactions utilized for degradation of lignins by wood-degrading fungi. Results from these experiments show that FeSO4 produced more ·OH than Fe-EDTA. The improved non-intrusive chemiluminescence assay has proven to be an excellent tool for investigating the role of the ·OH in biomimetic pulp bleaching and potentially other systems.

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