Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Superoxides”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

[Superoxide radical and superoxide dismutase in the free-radical theory of aging (a review)].

Review is presented on the role of superoxide radicals and other intermediates of single electron reduction of oxygen in aging as well as on geroprotective importance of superoxide dismutase. These factors are considered in relation with age. Significance of direct and indirect methods for estimation of total O2-radicals is analyzed. Possible role of O2-radicals and superoxide dismutase in regulation of cell division and differentiation is also discussed. Life span of cells in peripheric circulation correlates with superoxide dismutase content in these cells and their ability to generate exogenous O2-.

Aerobiosis↗
PubMed1983

Superoxide anion and hydrogen peroxide release by macrophages from mice treated with Nocardia rubra cell-wall skeleton: inhibition of macrophage cytotoxicity by a protease inhibitor but not by superoxide dismutase and catalase.

Peritoneal macrophages obtained from male BALB/c mice intraperitoneally injected with Nocardia rubra cell-wall skeleton (N-CWS) showed abundant superoxide anion and hydrogen peroxide release in response to opsonized zymosan used as a trigger. These N-CWS-induced macrophages also showed marked cytolytic activity against syngeneic Meth A fibrosarcoma targets. To examine the possible role of superoxide anion and/or hydrogen peroxide in the lysis of Meth A cells, N-CWS-induced macrophages were assayed with Meth A targets in the presence of superoxide dismutase, catalase, or both. However, addition of these agents to the assays, in doses which abolished detectable superoxide anion and/or hydrogen peroxide release from the effector cells, had no inhibitory effects on the cytotoxicity of N-CWS-induced macrophages. In contrast, both a protease inhibitor and actinomycin D could inhibit the cytolysis of Meth A targets by N-CWS-induced macrophages. These data raise the possibility that protease(s) rather than oxygen intermediates might be involved in the cytotoxicity of N-CWS-induced macrophages against tumor cells.

Animals↗
PubMed1984

The reaction of superoxide radical with catalase. Mechanism of the inhibition of catalase by superoxide radical.

We have studied the time course of the absorption of bovine liver catalase after pulse radiolysis with oxygen saturation in the presence and absence of superoxide dismutase. In the absence of superoxide dismutase, catalase produced Compound I and another species. The formation of Compound I is due to the reaction of ferric catalase with hydrogen peroxide, which is generated by the disproportionation of the superoxide anion (O-2). The kinetic difference spectrum showed that the other species was neither Compound I nor II. In the presence of superoxide dismutase, the formation of this species was found to be inhibited, whereas that of Compound I was little affected. This suggests that this species is formed by the reaction of ferric catalase with O-2 and is probably the oxy form of this enzyme (Compound III). The rate constant for the reaction of O-2 and ferric catalase increased with a decrease in pH (cf. 4.5 X 10(4) M-1 s-1 at pH 9 and 4.6 X 10(6) M-1 s-1 at pH 5.). The pH dependence of the rate constant can be explained by assuming that HO2 reacts with this enzyme more rapidly than O-2.

Animals↗
PubMed1994

Comparison of effects of margarite extract and recombinant human superoxide dismutase on paraquat-induced superoxide anion radicals in rat lung.

The effects of medicinal margarite extract and recombinant human superoxide dismutase (r-h SOD) on acute paraquat intoxication were examined in the rat lung. Forty-eight Sprague-Dawley rats under pentobarbital anesthesia were randomly assigned to one of four groups receiving i.v. injection of physiological saline (control), i.v. injection of 70 mg/kg paraquat, or i.v. injection of either 50 mg/kg of margarite extract or 50,000 unit/kg of r-h SOD 10 minutes before and 1 and 2 hours after an equivalent paraquat administration. Examination of lung superoxide anion radicals (O2-.), lipid peroxides, and histopathological changes showed that paraquat significantly increased superoxide anion radicals (383% of control) reacted with CLA-phenyl. Both margarite extract and r-h SOD decreased superoxide anion radicals to 119% and 83% of control, respectively. Margarite extract, rather than r-h SOD, significantly alleviated the paraquat-induced infiltration of polymorphonuclear leukocytes and macrophages into the alveolar walls. There were no significant inter-group differences in lipid peroxides in the lung. Component analysis showed that margarite extract was rich in L- and D-arginine. The scavenging mechanism of margarite extract may be related to L-arginine but needs to be further verified in the future study.

Animals↗
PubMed1998

Microtiter plate assay for superoxide dismutase using MTT reduction by superoxide.

A simple microtiter plate based colorimetric assay for superoxide dismutase is described. The method, involves generation of superoxide by pyrogallol autoxidation and the inhibition of superoxide dependent reduction of the tetrazolium dye MTT [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyl tetrazolium bromide] to its formazan, measured at 570 nm. The reaction was terminated by the addition of dimethyl sulfoxide (DMSO) which also helps to solubilize the formazan formed and the colour evolved was stable for many hours. The method was compared with other known methods to measure the activity of purified erythrocyte Cu,ZnSOD and superoxide dismutase activity from various rat tissues. This procedure involves inexpensive reagents, allows a rapid and sensitive measurement of SOD activity and the microtiter plate assay is suitable for use with large number of samples.

Animals↗
PubMed1989

Cobalt substitution studies on bovine erythrocyte superoxide dismutase: evidence for a novel cobalt-superoxide dismutase derivative.

Three cobalt derivatives of bovine erythrocyte superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) have been prepared under different pH conditions using a cobalt-thiocyanate complex which has already proved to yield specific substitutions on other copper proteins. The cobalt-protein derivatives have been characterized by optical, circular dichroism and fluorescence spectroscopies. One derivative, referred to as Co2Co2-protein, contains Co(II) ions specifically bound at both Zn(II) and Cu(II) sites. On the basis of their spectroscopic properties, the other two derivatives can be referred as E2Co2- and Co2E2-superoxide dismutase, with cobalt substituting, respectively, at the zinc and the copper sites leaving the contiguous site empty (E). The Co2E2-protein complex represents a novel derivative, since it has never been described in literature. The optical spectrum in the visible region of Co2-Co2-protein well corresponds to the sum of the spectra of the other two derivatives. The circular dichroism spectrum of Co2Co2-derivative, however, is not the sum of individual E2Co2- and Co2E2-proteins, suggesting that the presence of Co(II) in one site strongly affects the geometry of the neighbouring site. Some discrepancies between our spectroscopic data and those reported in literature are discussed. The results obtained from fluorescence experiments indicate that Co(II) ions exert a different quenching effect on the tyrosine emission, depending on whether they are located in the Zn(II) or in the Cu(II) site. The fluorescence quenching can be attributed to a 'heavy atom' and 'paramagnetic ion' effect by Co(II) ions.

Animals↗
PubMed1984

CuZn superoxide dismutase, Mn superoxide dismutase, catalase and glutathione peroxidase in glutathione-deficient human fibroblasts.

The effect of genetically determined glutathione deficiency on the fibroblast content of CuZn superoxide dismutase, Mn superoxide dismutase, catalase and glutathione peroxidase was investigated. No significant differences between glutathione-deficient and -proficient human fibroblasts were revealed. There was a large variation in the content of the investigated enzymes in fibroblasts grown and analysed on different occasions. Whereas the contents of CuZn superoxide dismutase, catalase and glutathione peroxidase did not deviate much from what has been found in other human cell-lines and tissues, the fibroblasts were found to contain exceptional amounts of Mn superoxide dismutase.

Adult↗
PubMed1987

Comparison of the inactivation of Bacillus subtilis transforming DNA by the potassium superoxide and xanthine-xanthine oxidase systems for generating superoxide.

Potassium superoxide (KO2) and xanthine-xanthine oxidase (X-XO), which are known generating systems for the superoxide anion, have different inactivating actions on Bacillus subtilis transforming DNA in vitro. Superoxide dismutase and CuSO4 enhanced the inactivation for KO2, but not for X-XO. Mannitol, a hydroxyl radical scavenger, protected against the inactivation by X-XO, but not by KO2. The results obtained with X-XO were consistent with the involvement of Fenton reactions, in which hydroxyl radical is the reactive species that ultimately causes damage. On the other hand, KO2-induced inactivation was partly due to the effect of H2O2. Differences in inactivation between the KO2 and X-XO systems may result from the different rates of production of the superoxide anion.

Bacillus subtilis↗
PubMed2006

Engineered superoxide dismutase monomers for superoxide biosensor applications.

Because of its high reaction rate and specificity, the enzyme superoxide dismutase (SOD) offers great potential for the sensitive quantification of superoxide radicals in electrochemical biosensors. In this work, monomeric mutants of human Cu,Zn-SOD were engineered to contain one or two additional cysteine residues, which could be used to bind the protein to gold surfaces, thus making the use of promotor molecules unnecessary. Six mutants were successfully designed, expressed, and purified. All mutants bound directly to unmodified gold surfaces via the sulfur of the cysteine residues and showed a quasi-reversible, direct electron transfer to the electrode. Thermodynamic and kinetic parameters of the electron transfer were characterized and showed only slight variations between the individual mutants. For one of the mutants, the interaction with the superoxide radical was studied in more detail. For both partial reactions of the dismutation, an interaction between protein and radical could be shown. In an amperometric biosensorial approach, the SOD-mutant electrode was successfully applied for the detection of superoxide radicals. In the oxidation region, the electrode surpassed the sensitivity of the commonly used cytochrome c electrodes by approximately 1 order of magnitude while not being limited by interferences, but the electrode did not fully reach the sensitivity of dimeric Cu,Zn-SOD immobilized on MPA-modified gold.

Biosensing Techniques↗
PubMed1997

Activity profile of placental superoxide-superoxide dismutase system in pregnant mice and its possible relation with placental steroidogenesis.

Placenta in mouse generate increasing quantities of superoxide dismutase from day 13 of pregnancy until parturition. This is associated with a concomitant reduction in the activity of superoxide radical. This findings points to the steroidogenic control of the later half of pregnancy by the placental axis. Parturition is associated with an abrupt spurt in superoxide radical. This is a novel finding and could be a consequence of the estrogen surge at labour. It is suggested that this abrupt increase in superoxide radical level at parturition may remould the placental membrane fluid at the point of its attachment with uterine membranes so as to facilitate the separation of placenta from uterus.

Animals↗
PubMed1984

The amino-acid sequence of copper/zinc superoxide dismutase from swordfish liver. Comparison of copper/zinc superoxide dismutase sequences.

The amino acid sequence of copper/zinc superoxide dismutase from swordfish (Xiphias gladius) liver has been determined by alignment of the tryptic peptides according to the known sequence of bovine erythrocyte copper/zinc superoxide dismutase. This alignment has resulted in the ligands to the copper (His-47, 49, 76 and 94) and the zinc (His-76, 85, 134 and Asp-97) being conserved in all the copper/zinc superoxide dismutases sequenced so far. Also conserved in the sequences are the cysteines forming the intrachain disulphide bridge (Cys-58 and 160) and the essential arginine (Arg-157). Comparison of the amino acid sequence of swordfish liver copper/zinc superoxide dismutase with the bovine, human, horse, yeast and Photobacterium leiognathi indicates that the swordfish enzyme has a high homology with the other eukaryotic enzymes. Low homology is, however, observed with the P. leiognathi enzyme.

Amino Acid Sequence↗
PubMed1995

The pH-dependent changes of the enzymic activity and spectroscopic properties of iron-substituted manganese superoxide dismutase. A study on the metal-specific activity of Mn-containing superoxide dismutase.

Manganese-containing superoxide dismutases (Mn-SODs) and iron-containing superoxide dismutases (Fe-SODs) from aerobic bacteria often show high metal specificity for their enzymic activities by a standard assay system using xanthine-xanthine oxidase and cytochrome c. In this study, we have attempted to characterize the structural basis of the metal specificity of manganese-containing SOD (Mn-SOD) using Fe-substituted Mn-SOD prepared from apo-Mn-SOD from Serratia marcescens. The Fe3+ content of the Fe-substituted enzyme was 1.71 +/- 0.14 mol/mol dimer and the specific activity was 34.8 +/- 4.8 units.mg protein-1.mol Fe3+(-1).mol subunit-1. Fe-substituted Mn-SOD was found to react with the superoxide anion at pH 8.1 with a second-order rate constant of 6 x 10(6) M-1 s-1, which is approximately 1% of that of native Mn-SOD at the same pH. However, the rate constant increased with decreasing pH to approximately 10% (5 x 10(7) M-1 s-1) that of native Mn-SOD at pH 6.0 with a pK of 7.0. The visible absorption spectrum and EPR spectrum of Fe-substituted Mn-SOD also showed pH-dependent changes with pK values of 6.6 and 7.2, respectively. Similarly, the affinity of the azide ion, an analog of the superoxide ion, for iron of Fe-substituted Mn-SOD increased with decreasing pH, with a pK value of 7.0 (e.g. Kd = 0.1 mM at pH 6.2 and 0.9 mM at pH 8.2). The similarity of these pK values suggests that the activity, the spectral changes and the affinity of the azide ion for iron are derived from the same change in the metal environment. After comparison with the reported pK values (around 9) of similar pH-dependent changes in the spectra, the enzymic activity and the affinity of azide for iron of Fe-SOD from Escherichia coli, we proposed that the difference in the pK values of a hydroxide ion binding to iron between Fe-substituted Mn-SOD and Fe-SOD may cause the different pH dependencies of these changes in each SOD.

Azides↗
PubMed1985

The primary structure of porcine Cu-Zn superoxide dismutase. Evidence for allotypes of superoxide dismutase in pigs.

Cu-Zn superoxide dismutase was purified to homogeneity from mixed pig blood and from a single pig. The isolated product had an absorption ratio 280/260 nm of 0.91, a specific activity of 3 000 +/- 200 units (cytochrome c reduction test), and an isoelectric point of 7.5 (chromatofocusing) or 7.25 (isoelectric focusing), respectively. Sequence determination was performed by automated solid-phase Edman degradation of fragments of the reduced S-carboxymethylated proteins obtained by digestion with trypsin or Staphylococcus aureus proteinase V8 or treatment with cyanogen bromide. Acetylation of the N-terminus was confirmed by comparing high performance liquid chromatography retention times of N-terminal peptides with those of authentic samples. Sequencing of the superoxide dismutase of mixed porcine blood revealed heterogeneity (70% Leu; 30% Val at position 29), whereas the sample derived from a single French pig proved to be homogeneous (100% Leu at position 29). The complete sequence of pig superoxide dismutase comprised 152 amino-acid residues, which corresponds to a theoretical molecular mass of 15 800 Da per subunit, and exhibited the expected high homology with those of other mammals. The aspartate and all 7 histidine residues known to complex the metal ions in bovine superoxide dismutase are conserved in the porcine sequence at the homologous positions Asp82 and His45, His47, His62, His70, His79, His119, respectively.

Amino Acid Sequence↗
PubMed1988

From haemocuprein to copper-zinc superoxide dismutase: a history on the fiftieth anniversary of the discovery of haemocuprein and the twentieth anniversary of the discovery of superoxide dismutase.

Haemocuprein was discovered fifty years ago by T. Mann and D. Keilin as a copper protein of red blood cells, later named erythrocuprein. Superoxide dismutase was discovered twenty years ago by J.M. McCord and I. Fridovich as an enzymatic activity in preparations of carbonic anhydrase or myoglobin that inhibited the aerobic reduction of cytochrome c by xanthine oxidase. Astonishingly the superoxide dismutase proved to be haemocuprein. Around this time zinc was found in haemocuprein, in equimolar amount to the copper. Haemocuprein thus became copper-zinc superoxide dismutase after thirty years as an obscure cuproprotein of red blood cells. This historical article is a tribute to the achievement of J.M. McCord and I. Fridovich. Their discovery of superoxide dismutase revolutionized the study of oxygen free-radicals in biochemistry.

Animals↗
PubMed2004

Attenuation of renal injury in db/db mice overexpressing superoxide dismutase: evidence for reduced superoxide-nitric oxide interaction.

The effects of overexpression of Cu(2+)/Zn(2+) superoxide dismutase-1 (SOD-1) on indexes of renal injury were compared in 5-month-old nontransgenic (NTg) db/db mice and db/db mice hemizygous for the human SOD-1 transgene (SOD-Tg). Both diabetic groups exhibited similar hyperglycemia and weight gain. However, in NTg-db/db mice, albuminuria, glomerular accumulation of immunoreactive transforming growth factor-beta, collagen alpha1(IV), nitrotyrosine, and mesangial matrix were all significantly increased compared with either nondiabetic mice or SOD-Tg-db/db. SOD-1 activity and reduced glutathione levels were higher, whereas malondialdehyde content was lower, in the renal cortex of SOD-Tg-db/db compared with NTg-db/db mice, consistent with a renal antioxidant effect in the transgenic mice. Inulin clearance (C(IN)) and urinary excretion of guanosine 3',5'-cyclic monophosphate (U(cGMP)) were increased in SOD-Tg-db/db mice compared with corresponding values in nondiabetic mice or NTg-db/db mice. C(IN) and U(cGMP) were suppressed by Nomega-nitro-L-arginine methyl ester in SOD-Tg-db/db but not in NTg-db/db mice, implying nitric oxide (NO) dependence of these increases and enhanced renal NO bioactivity in SOD-Tg-db/db. Studies of NO-responsive cGMP in isolated glomeruli supported greater quenching of NO in glomeruli from NTg-db/db compared with SOD-Tg-db/db mice. Evidence of increased NO responsiveness and the suppression of glomerular nitrotyrosine may both reflect reduced NO-superoxide interaction in SOD-Tg-db/db mice. The results implicate superoxide in the pathogenesis of diabetic nephropathy.

Animals↗
PubMed1997

Superoxide-mediated cytotoxicity in superoxide dismutase-deficient fetal fibroblasts.

To investigate the roles of CuZn superoxide dismutase (CuZnSOD) and Mn superoxide dismutase (MnSOD) in oxygen radical-mediated cytotoxicity and to distinguish the actions of these two enzymes, fetal fibroblasts were derived from mouse fetuses that are either deficient in CuZnSOD (Sod1-/+ and -/-) or MnSOD (Sod2-1+ and -/-) for in vitro studies. Whereas the phenotype of the Sod1 mutant animals did not differ from that of their normal littermates, the growth of Sod1-/- fetal fibroblasts was only 25% of that of the -/+ and +/+ cells. On the other hand, although almost all homozygous Sod2 mutant animals (-/-) died within 10 days after birth, cultivation of Sod2-/- fetal fibroblasts was possible and their growth was about 60% that of -/+ and +/+ cells. When cultured cells were subjected to treatment with paraquat to assess their ability to grow in the presence of high levels of superoxide radicals, Sod1-/- cells were 80 times more sensitive and Sod2-/- cells were 12 times more sensitive to paraquat than wild-type cells. In addition, whereas the loss of 50% CuZnSOD rendered Sod1-/+ cells almost twice more sensitive to paraquat than +/+ cells, loss of 50% MnSOD had no effect on paraquat sensitivity. Our results suggest that CuZnSOD-deficient cells are more sensitive to oxygen toxicity than are MnSOD-deficient cells, that paraquat causes free radical-induced damage in both the mitochondria and cytoplasm, and that SOD compartmentalized in the cytosol cannot compensate for the loss of SOD in the mitochondria and vice versa.

Animals↗
PubMed1995

Microplate superoxide dismutase assay employing a nonenzymatic superoxide generator.

The antioxidant enzyme superoxide dismutase (EC 1.15.1.1) (SOD) catalyzes the conversion of superoxide anion radical (O2.-) to hydrogen peroxide and molecular oxygen. SOD helps prevent tissue damage by O2.- and its metabolites, and augmentation of tissue SOD is a useful therapeutic strategy in certain diseases having an oxidative-injury component. Routine application of direct SOD assays is not technically facile, since the short half-life of the O2.- substrate and its free radical nature necessitate specialized analytical equipment to detect and measure O2.- chemically. Consequently, indirect SOD assays which monitor some change in an indicator substance reacting with O2.- are routinely used, particularly for biological samples. Limitations of indirect test systems utilizing heme-based indicators for the presence of O2.- and/or enzymatic O2.- generators led us to develop a SOD microassay based on spectrophotometric assessment of O2.- mediated nitro blue tetrazolium reduction by an aerobic mixture of NADH and phenazine methosulfate, which produces superoxide chemically at nonacidic pH (Rao, Free Radical Biol. Med. 7, 513-519, 1989). The proposed SOD assay system is formatted for use in an automated 96-well microplate reader and has the virtues of a nonheme indicator, a nonenzymatic O2.- source, physiological pH, and economy of time and materials. The assay has been applied to measure purified and tissue SOD (Cu,Zn- and Mn-types) activity as well as O2.- turnover by small-molecule "SOD mimetics."

Animals↗
PubMed1985

Superoxide dismutase inhibits the superoxide-driven Fenton reaction at two different levels. Implications for a wider protective role.

Superoxide dismutase (SOD) completely inhibits the damage caused by a ferric-EDTA chelate in the presence of a superoxide-generating system. In this reaction superoxide is enzymically dismuted to hydrogen peroxide. Since hydrogen peroxide and a ferric-EDTA chelate are themselves a hydroxyl radical-generating system, it follows that SOD must also protect against damage done by this reaction. The ability of SOD to inhibit damage to deoxyribose caused by hydrogen peroxide and a ferric-EDTA chelate is experimentally demonstrated in this paper.

Chemical Phenomena↗