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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of copper sulfate (CuSO4) on both hepatic oxidative stress and heme oxygenase induction was studied. A strong increase in in vivo rat liver chemiluminescence was observed 1 h after Cu(II) administration. To evaluate liver antioxidant enzymatic defenses, superoxide dismutase, catalase, and glutathione peroxidase activities were determined. Catalase and glutathione peroxidase were found to be significantly decreased 5 h after CuSO4 injection. In contrast, superoxide dismutase activity was increased. Heme oxygenase activity appeared 5 h after treatment, reaching a maximum value 18 h after CuSO4 administration. This induction was preceded by a decrease in the intrahepatic GSH pool and an increase in the generation of thiobarbituric acid reactive substances, both effects taking place a number of hours before induction of heme oxygenase. Administration of bilirubin, the end product of heme catabolism in mammals, and alpha-tocopherol, a widely employed antioxidant, completely prevented heme oxygenase induction as well as the decrease in hepatic GSH and the increase in chemiluminescence when administered 2 h before CuSO4 treatment. Under the same experimental conditions, beta-carotene showed a moderate preventive effect on both heme oxygenase induction and oxidative stress parameters. These data obtained with Cu(II) treatment are in agreement with our previous reports suggesting a correlation between heme oxygenase induction and oxidative stress.
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PMID:Relationship between oxidative stress and heme oxygenase induction by copper sulfate. 901 30

In aqueous solutions containing Cu(II) ions and ascorbic acid, thiamine was observed to be oxidized to the fluorescent products thiochrome and oxodihydrothiochrome in neutral and acid media. At high initial concentrations of thiamine, thiochrome was practically the only product of thiamine oxidation. Catalase inhibited the oxidation rate approximately by 30-fold, whereas superoxide dismutase reduced the rate by only 2.5-fold. Aliphatic alcohols, glucose, and high concentrations of ascorbic acid effectively inhibited the production of thiochrome. The yield of thiochrome was also decreased in the presence of aliphatic amino acids, histidine, and particularly human serum albumin (HSA). With complete binding of copper ions by HSA, no formation of fluorescent products was observed. In neutral and acidic media under the action of hydroxyl radicals, thiamine formed a tricyclic semiquinone form which was then oxidized to thiochrome by superoxide anion or H2O2. Ascorbic acid played the main role in the reduction of Cu(II), whereas the contribution of superoxide anions was less significant. Cu(I) interacted with H2O2 to form hydroxyl radicals. The addition of H2O2 both to thiamine and to the mixture of thiamine and Cu(II) ions did not lead to significant production of thiochrome in neutral and acidic media.
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PMID:Thiamine oxidative transformations catalyzed by copper ions and ascorbic acid. 948 73

Aluminum is known to enhance the ability of iron to promote the generation of reactive oxygen species (ROS) but the mechanism subserving this is unknown. In an attempt to understand the means by which this potentiation occurs, several types of experiment have been conducted. It was found that iron must be in the ferrous form for aluminum-based stimulation of ROS to take place in a cerebral cortical synaptosomal-mitochondrial fraction. The ability of other transition metals of varying valences, copper and chromium, to catalyze formation of ROS was also increased in the presence of aluminum. Catalase but not superoxide dismutase blocked such stimulation suggesting hydrogen peroxide as an intermediate. The formation of aluminosilicates in the presence of brain tissue did not enhance iron-stimulated ROS formation. Furthermore, configurational changes of proteins which have been proposed to account for this phenomenon, do not appear to be a key element since iron-aluminum potentiation could be observed using protein-free liposomal micelles bearing an external negative charge.
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PMID:Mechanisms underlying the aluminum-induced potentiation of the pro-oxidant properties of transition metals. 949 22

Scission of plant cell wall polysaccharides in vivo has generally been assumed to be enzymic. However, in the presence of l-ascorbate, such polysaccharides are shown to undergo non-enzymic scission under physiologically relevant conditions. Scission of xyloglucan by 1 mM ascorbate had a pH optimum of 4.5, and the maximum scission rate was reached after a 10-25-min delay. Catalase prevented the scission, whereas added H2O2 (0.1-10 mM) increased the scission rate and shortened the delay. Ascorbate caused detectable xyloglucan scission above approx. 5 microM. Dehydroascorbate was much less effective. Added Cu2+ (>0.3 microM) also increased the rate of ascorbate-induced scission; EDTA was inhibitory. The rate of scission in the absence of added metals appeared to be attributable to the traces of Cu (2.8 mg.kg-1) present in the xyloglucan. Ascorbate-induced scission of xyloglucan was inhibited by radical scavengers; their effectiveness was proportional to their rate constants for reaction with hydroxyl radicals (.OH). It is proposed that ascorbate non-enzymically reduces O2 to H2O2, and Cu2+ to Cu+, and that H2O2 and Cu+ react to form .OH, which causes oxidative scission of polysaccharide chains. Evidence is reviewed to suggest that, in the wall of a living plant cell, Cu+ and H2O2 are formed by reactions involving ascorbate and its products, dehydroascorbate and oxalate. Systems may thus be in place to produce apoplastic .OH radicals in vivo. Although .OH radicals are often regarded as detrimental, they are so short-lived that they could act as site-specific oxidants targeted to play a useful role in loosening the cell wall, e.g. during cell expansion, fruit ripening and organ abscission.
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PMID:Oxidative scission of plant cell wall polysaccharides by ascorbate-induced hydroxyl radicals. 960 Oct 81

The promutagenic base 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA is known to be formed from oxygen radical attack on 2'-deoxyguanosine (dG) as a result of oxidative stress. Formation of 8-OH-dG from dG during workup is strongly dependent on temperature and transition metals and is mediated by oxygen radicals. The 8-OH-dG formation at temperatures between 0 and 140 degrees C for 1.5 h in an "ultrapure" solution followed a third-order equation. Fe2+ in the nM range mediated the formation of 8-OH-dG from dG without addition of H2O2. Fe3+, Cu+, and Cu2+ were shown to have weaker oxidative effects in comparison to Fe2+. The pH (5.0-9.0) had a very limited effect on 8-OH-dG formation. Acid phosphatase, which contains iron at its active site, caused the formation of 8-OH-dG, whereas alkaline phosphatase did not. Phenol was not found to be oxidative. Fe2+-catalyzed formation of 8-OH-dG was completely blocked by the nitroxide 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), whereas DMSO, mannitol, and DMPO had a significantly weaker protecting effect. Catalase cleaved the dG molecule and was not suitable for use. A simple, fast, and inexpensive method for 8-OH-dG workup and analysis was developed, and the background level seen in liver from 13-week-old male Sprague-Dawley rat was 0.23 +/- 0.020 8-OH-dG/10(5) dG, which is up to 200 times lower than reported values from some other methods and up to 26 times lower when compared to other reports using HPLC-EC methods. In summary, the TEMPO method reduces oxidation of dG to 8-OH-dG during workup by (1) using chemicals low in transition metals, (2) using a cold workup procedure, (3) limiting the incubation time, and (4) using the nitroxide TEMPO in all steps.
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PMID:Reduction of oxidation during the preparation of DNA and analysis of 8-hydroxy-2'-deoxyguanosine. 970 49

We examined the mechanism of DNA damage induced by a mutagenic tyrosine metabolite, homogentisic acid (HGA), using 32P-5'-end-labeled DNA fragments obtained from the human p53 tumor suppressor gene. HGA caused DNA damage in the presence of Cu(II), particularly at thymine and cytosine residues. Catalase and bathocuproine inhibited the DNA damage, suggesting the involvement of H2O2 and Cu(I). The formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine by HGA increased depending on HGA concentration in the presence of Cu(II). It is concluded that H2O2 is generated during Cu(II)-catalyzed HGA autoxidation and reacts with Cu(I) to form the Cu(I)-peroxide complex, capable of causing oxidative DNA damage.
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PMID:Oxidative DNA damage induced by homogentisic acid, a tyrosine metabolite. 971 Feb 41

The ability of Cu(II) and Fe(III) to promote site-specific DNA damage in the presence of endogenous reductants was investigated by using 32P-5'-end-labeled DNA fragments obtained from the human p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene. Ascorbate induced metal-dependent DNA damage most efficiently (ascorbate > GSH > NADH). Cu(II) induced endogenous reductants-dependent DNA damage more efficiently than Fe(III). Endogenous reductants plus Fe(III) caused DNA cleavage at every nucleotide, without marked site preference. DNA damage by Fe(III) was inhibited by hydroxyl free radical (.OH) scavengers and catalase. These results suggest that endogenous reductants plus Fe(III) generate free or extremely near free .OH via H2O2 formation, and that .OH causes DNA damage. In the presence of 50 microM Cu(II) in bicarbonate buffer, ascorbate caused DNA cleavage frequently at sites of two or more adjacent guanine residues. In contrast, in the presence of 20 microM Cu(II), ascorbate caused DNA cleavage frequently at thymine residues. Catalase and a Cu(I)-specific chelator inhibited DNA damage by Cu(II), whereas .OH scavengers did not. Fe(III)-dependent 8-oxo-7,8-dihydro-2'-deoxyguanosine formation was inhibited by .OH scavengers, whereas no inhibition by .OH scavengers was observed with Cu(II). These results suggest that .OH is the main active species formed with Fe(III), whereas copper-peroxide complexes with a reactivity similar to .OH participate in Cu(II)-dependent DNA damage. The polyguanosine sequence specificity of DNA damage in the presence of high concentrations of Cu(II) can be explained by the preferential binding of Cu(II) to guanine residues.
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PMID:Distinct mechanisms of site-specific DNA damage induced by endogenous reductants in the presence of iron(III) and copper(II). 971 16

Alloxan is known to induce diabetes in experimental animals through destruction of insulin-producing 3-cells of pancreas. The mechanism of DNA damage induced by alloxan was investigated using 32P-labeled human DNA fragments. Cu(II)-dependent DNA damage increased with the concentration of alloxan and NADH. Alloxan induced DNA cleavage frequently at thymine and cytosine residues in the presence of NADH and Cu(II). Catalase and bathocuproine, a Cu(I)-specific chelator, almost completely inhibited DNA damage, suggesting the involvement of H2O2 and Cu(I). Alloxan induced Cu(II)-dependent production of 8-oxodG in calf thymus DNA in the presence of NADH. UV-visible and electron spin resonance (ESR) spectroscopic studies showed that superoxide anion radical and alloxan radical were generated by the reduction of alloxan by NADH, and also by the autoxidation of dialuric acid, the reduced form of alloxan. These results suggest that the copper-oxygen complex derived from the reaction of H2O2 with Cu(I) participates in Cu(II)-dependent DNA damage by alloxan plus NADH and dialuric acid. The mechanism of DNA damage is discussed in relation to diabetogenic action of alloxan.
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PMID:Metal-mediated DNA damage induced by diabetogenic alloxan in the presence of NADH. 974 96

DNA damage by metabolites of a food additive, butylated hydroxytoluene (BHT), was investigated as a potential mechanism of carcinogenicity. The mechanism of DNA damage by 2,6-di-tert-butyl-p-benzoquinone (BHT-quinone), 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHT-OOH), and 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) in the presence of metal ions was investigated by using 32P-labeled DNA fragments obtained from the c-Ha-ras-1 proto-oncogene and the p53 tumor suppressor gene. BHT-OOH caused DNA damage in the presence of Cu(II), whereas BHT-quinone and BHT-CHO did not. However, BHT-quinone did induce DNA damage in the presence of NADH and Cu(II). Bathocuproine inhibited Cu(II)-mediated DNA damage, indicating the participation of Cu(I) in the process. Catalase also inhibited DNA damage induced by BHT-quinone, but not that induced by BHT-OOH. The DNA cleavage pattern observed with BHT-quinone plus NADH was different from that seen with BHT-OOH. With BHT-quinone plus NADH, piperidine-labile sites could be generated at nucleotides other than adenine residue. BHT-OOH caused cleavage specifically at guanine residues. Pulsed field gel electrophoresis showed that BHT-OOH and BHT-quinone induced DNA strand breaks in cultured cells, whereas BHT-CHO did not. Both BHT-quinone and BHT-OOH induced internucleosomal DNA fragmentation, which is the characteristic of apoptosis. Furthermore, flow cytometry analysis revealed an increase of peroxides in cultured cells treated with BHT-OOH or BHT-quinone. These results suggest that BHT-OOH participates in oxidative DNA damage directly, whereas BHT-quinone causes DNA damage through H2O2 generation, which leads to internucleosomal DNA fragmentation.
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PMID:Oxidative DNA damage and apoptosis induced by metabolites of butylated hydroxytoluene. 974 74

In the framework of an INTAS project, arctic populations of the clam Macoma balthica were collected from seven stations (Mezen, Khaypudyr, Pechora 3, Pechora 5, Dvina, Keret 1, and Keret 2) in the White Sea and Pechora Sea. The main objectives of this research were to define baseline concentrations of trace metals (As, Cd, Cr, Cu, Fe, Mn, Pb, Zn) in M. balthica and to evaluate antioxidant responses as biomarkers of anthropogenic stress in these organisms. The antioxidant parameters examined included the levels of glutathione and the activities of several glutathione-dependent and antioxidant enzymes: glyoxalase I and glyoxalase II (EC 4.4.1.5 and EC 3.1.2.6), glutathione S-transferases (EC 2.5.1.18), glutathione reductase (EC 1.6.4.2), glutathione peroxidases (EC1.11.1.9 and EC 2.5.1.18, respectively, for Se-dependent and Se-independent forms), superoxide dismutase (SOD, EC 1.15.1.1), and catalase (EC 1.11.1.6). Organisms revealed enhanced concentrations of lead in both Keret stations, Khaypudyr, and Mezen, and high levels of copper in Keret and cadmium in Khaypudyr. At the biochemical level, organisms from Pechora 3, Pechora 5, and Dvina were not statistically different, whereas those from Mezen and Khaypudyr exhibited higher activities of superoxide dismutase, glutathione peroxidase, and glyoxalase II. Catalase levels were lower in Mezen and Khaypudyr. More heterogeneous were the responses of glyoxalase I and glutathione S-transferases, while no significant differences among the stations were observed for glutathione reductase. Multiple regression analyses revealed significant positive relationships between the main antioxidant enzymes (glutathione peroxidases, superoxide dismutase, glyoxalase I, and glyoxalase II), and confirmed the exception of catalase, which, when significant, was negatively correlated with the other parameters. The results support the suitability of antioxidant responses as biomarkers of pollutant exposure and/or toxicity for arctic biomonitoring programs even though only moderately polluted sites were sampled.
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PMID:Trace metals and variations of antioxidant enzymes in Arctic bivalve populations. 977 77


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