Generation of Superoxide Radical during Autoxidation of Hydroxylamine and an Assay for Superoxide Dismutase
01 Feb 1978-Archives of Biochemistry and Biophysics (Arch Biochem Biophys)-Vol. 186, Iss: 1, pp 189-195
TL;DR: Hydrogen peroxide stimulated the autoxidation and superoxide dismutase inhibited the hydrogen peroxide-induced oxidation, results which suggest the participation of hydrogenperoxide in autoxidated and in the generation of superoxide radical.
About: This article is published in Archives of Biochemistry and Biophysics.The article was published on 1978-02-01. It has received 1480 citations till now. The article focuses on the topics: Autoxidation & Reactive oxygen species.
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TL;DR: O2- oxidizes the [4Fe-4S] clusters of dehydratases, such as aconitase, causing-inactivation and release of Fe(II), which may then reduce H2O2 to OH- +OH..
Abstract: O2- oxidizes the [4Fe-4S] clusters of dehydratases, such as aconitase, causing-inactivation and release of Fe(II), which may then reduce H2O2 to OH- +OH.. SODs inhibit such HO. production by scavengingO2-, but Cu, ZnSODs, by virtue of a nonspecific peroxidase activity, may peroxidize spin trapping agents and thus give the appearance of catalyzing OH. production from H2O2. There is a glycosylated, tetrameric Cu, ZnSOD in the extracellular space that binds to acidic glycosamino-glycans. It minimizes the reaction of O2- with NO. E. coli, and other gram negative microorganisms, contain a periplasmic Cu, ZnSOD that may serve to protect against extracellular O2-. Mn(III) complexes of multidentate macrocyclic nitrogenous ligands catalyze the dismutation of O2- and are being explored as potential pharmaceutical agents. SOD-null mutants have been prepared to reveal the biological effects of O2-. SodA, sodB E. coli exhibit dioxygen-dependent auxotrophies and enhanced mutagenesis, reflecting O2(-)-sensitive biosynthetic pathways and DNA damage. Yeast, lacking either Cu, ZnSOD or MnSOD, are oxygen intolerant, and the double mutant was hypermutable and defective in sporulation and exhibited requirements for methionine and lysine. A Cu, ZnSOD-null Drosophila exhibited a shortened lifespan.
3,298 citations
01 Jan 1987
TL;DR: After consideration of the question of superoxide toxicity and superoxide pathology, several areas in which SOD has been investigated or used as a tool in a biochemical, pharmacological, or clinical context are discussed.
Abstract: The current status of superoxide dismutase (SOD) is that it is an enzyme with diverse ramifications. This review attempts an understanding of SOD as a structural, functional, and biological entity. Accordingly, the review is in three parts. The first part discusses SOD in terms of protein structure, proceeding from primary to secondary and three-dimensional structure for the three forms of SOD: copper/zinc SOD, manganese SOD, and iron SOD. This is the order of structural knowledge of the enzyme. Iron SOD is an enzyme of prokaryotes and some higher plants. Manganese SOD is an enzyme of prokaryotes and eukaryotes. Copper/zinc SOD is an enzyme of eukaryotes and certain prokaryotes. The evolutionary relationships of the three forms of SOD, the status of the copper/zinc SOD gene in prokaryotes, and the cloning and sequencing of SOD genes are discussed. The second part of the review deals with the catalytic mechanism of SOD in the three forms of the enzyme. Structural and mechanistic conclusions from various spectroscopic studies are critically considered. A detailed picture is given of the active site of copper/zinc SOD. The third part is a review of SOD in the general context of oxygen toxicity. After consideration of the question of superoxide toxicity and superoxide pathology, several areas in which SOD has been investigated or used as a tool in a biochemical, pharmacological, or clinical context are discussed, including population genetics; trisomy 21; development and senescence; the nutritional copper, zinc, and manganese status; hemolysis and anemia; oxygen toxicity in the lung and nervous system; inflammation, autoimmune disease and chromosome breakage, ischemia and degenerative changes; radiation damage; and malignancy. A comprehensive picture is given of measurements of SOD activity in disease states, and the question of superoxide-related disease is considered at several points.
866 citations
TL;DR: The results of this systematic study on the in vitro interactions of 7-20 nm spherical silver nanoparticles with HT-1080 and A431 cells can be used to define a safe range of SNP for the intended application as a topical antimicrobial agent after appropriate in vivo studies.
670 citations
TL;DR: Interestingly, SNP exhibited good anti-inflammatory properties as indicated by concentration-dependent inhibition of marker enzymes (matrix metalloproteinase 2 and 9), which clearly indicate that silver nanoparticles could provide a safer alternative to conventional antimicrobial agents in the form of a topical antimicrobial formulation.
Abstract: Silver is an effective antimicrobial agent with low toxicity, which is important especially in the treatment of burn wounds where transient bacteremia is prevalent and its fast control is essential. Drugs releasing silver in ionic forms are known to get neutralized in biological fluids and upon long-term use may cause cosmetic abnormality, e.g., argyria and delayed wound healing. Given its broad spectrum activity, efficacy and lower costs, the search for newer and superior silver based antimicrobial agents is necessary. Among the various options available, silver nanoparticles have been the focus of increasing interest and are being heralded as an excellent candidate for therapeutic purposes. This report gives an account of our work on development of an antimicrobial gel formulation containing silver nanoparticles (SNP) in the size range of 7−20 nm synthesized by a proprietary biostabilization process. The typical minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against ...
545 citations
TL;DR: The findings of the present investigation provide a rational use of oxidative stress biomarkers in aquatic ecosystem pollution biomonitoring in Indian freshwater fish Wallago attu, also the first such attempt reported from India.
486 citations
References
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TL;DR: The autoxidation of pyrogallol was investigated in the presence of EDTA in the pH range 7.9–10.6, indicating an almost total dependence on the participation of the superoxide anion radical, O2·−, in the reaction.
Abstract: The autoxidation of pyrogallol was investigated in the presence of EDTA in the pH range 7.9–10.6.
The rate of autoxidation increases with increasing pH. At pH 7.9 the reaction is inhibited to 99% by superoxide dismutase, indicating an almost total dependence on the participation of the superoxide anion radical, O2·−, in the reaction. Up to pH 9.1 the reaction is still inhibited to over 90% by superoxide dismutase, but at higher alkalinity, O2·− -independent mechanisms rapidly become dominant.
Catalase has no effect on the autoxidation but decreases the oxygen consumption by half, showing that H2O2 is the stable product of oxygen and that H2O2 is not involved in the autoxidation mechanism.
A simple and rapid method for the assay of superoxide dismutase is described, based on the ability of the enzyme to inhibit the autoxidation of pyrogallol.
A plausible explanation is given for the non-competitive part of the inhibition of catechol O-methyltransferase brought about by pyrogallol.
9,030 citations
TL;DR: It is proposed that the autoxidation of epinephrine proceeds by at least two distinct pathways, only one of which is a free radical chain reaction involving O2- and hence inhibitable by superoxide dismutase.
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TL;DR: Clostridial and spinach ferredoxins, reduced enzymatically by the action of ferredoxin-TPN+ oxidoreductase, have been shown to carry out the univalent reduction of oxygen.
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TL;DR: The results point to a reaction between H2O2 and O2- (Haber-Weiss reaction) as a major source of the ·OH radicals and to a combined action of blocking ·OH formation as well as accelerating its removal.
896 citations