The Role of Superoxide Anion in the Autoxidation of Epinephrine and a Simple Assay for Superoxide Dismutase
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.
About: This article is published in Journal of Biological Chemistry.The article was published on 1972-05-25 and is currently open access. It has received 7872 citations till now. The article focuses on the topics: Autoxidation & Adrenochrome.
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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: 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
TL;DR: The reactive superoxide radical, O2-, formerly of concern only to radiation chemists and radiobiologists, is now understood to be a normal product of the biological reduction of molecular oxygen.
Abstract: The reactive superoxide radical, O2-, formerly of concern only to radiation chemists and radiobiologists, is now understood to be a normal product of the biological reduction of molecular oxygen. An unusual family of enzymes, the superoxide dismutases, protect against the deleterious actions of this radical by catalyzing its dismutation to hydrogen peroxide plus oxygen.
3,273 citations
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.
1,480 citations
1,475 citations
References
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TL;DR: The demonstration that O2·- can reduce ferricytochrome c and tetranitromethane, and that superoxide dismutase, by competing for the superoxide radicals, can markedly inhibit these reactions, is demonstrated.
12,468 citations
TL;DR: The staining procedure for localizing superoxide dismutase on polyacrylamide electrophoretograms has been applied to extracts obtained from a variety of sources and could thus be assayed either in crude extracts or in purified protein fractions.
10,933 citations
TL;DR: The data are consistent with the conclusion that xanthine oxidase generates an unstable reduced form of oxygen, presumably the superoxide anion, and that this radical is the agent which directly reduces cytochrome c and initiates the sulfite-oxygen chain reaction.
1,163 citations
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.
1,036 citations
601 citations