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

This study has investigated the kinetics and mechanism of ultraweak luminescence in maize roots. Mannitol induced the second maximum and enhanced the main maximum of the relative intensity of luminescence from the roots. Hydroquinone and quinone enhanced the relative intensity of the luminescence. Catalase enhanced the maximum of the luminescence and changed the kinetics of the light emission. The effect of catalase on the kinetics was abolished by superoxide dismutase. Ascorbate in the presence of catalase on the kinetics was abolished by superoxide dismutase. Ascorbate in the presence of catalase reduced the luminescence maximum, but did not alter the kinetics. In the presence of catalase only, or in the combination with superoxide dismutase, or ascorbate, the luminescence intensity in the stationary phase was significantly lower compared to the control. The results support the participation of superoxide-radical, singlet oxygen, electron transfer and the role of peroxidase in the reactions generating ultraweak luminescence in the roots. Ascorbate, catalase and superoxide dismutase have a protective role in the luminescent reactions.
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PMID:Effect of propagators and inhibitors on the ultraweak luminescence from maize roots. 217 39

Chondrocytes in dense suspension culture in agarose survive in serum-free DME because they secrete low molecular mass compounds supporting their own viability. This activity can be replaced by pyruvate, or sulfhydryl compounds, e.g., cysteine or dithioerythritol. Catalase, an enzyme decomposing H2O2, also protects the cells, whereas superoxide dismutase has no effect. Therefore, chondrocytes in culture are sensitive to toxic compounds derived from molecular oxygen, i.e., hydroxyl radicals or hydrogen peroxide spontaneously generated in DME containing ascorbate and ferrous ions. Poly-ADP-ribosylation is an important step in the cascade of events triggered by these compounds. To survive, chondrocytes do not require stimulation by growth factors. They remain resting cells in fully defined, serum-free culture also at low density. Proliferation and hypertrophy can be induced by serum, but not by low cell density alone.
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PMID:Resting chondrocytes in culture survive without growth factors, but are sensitive to toxic oxygen metabolites. 236 33

Several enzymatic and nonenzymatic reactions play important roles in the physiologic neutralization of hydrogen peroxide (H2O2) in the anterior segment of the eye. The nonenzymatic reactions are particularly important in the aqueous humor, where enzymes are normally absent and high levels of ascorbate are present. One of ascorbate's presumed functions is to protect the lens and retina from the damaging effects of ultraviolet radiation. It also appears to act as an antioxidant for the removal of H2O2. Although H2O2 is frequently a product of antioxidant reactions, the low oxygen tension of the aqueous humor and the absence of trace elements apparently account for the relatively low concentrations of H2O2. This property of aqueous humor is important because high concentrations of H2O2 are toxic to both the lens and the cornea. This damage is exacerbated by the removal of glucose or by inhibition of glutathione reductase--an indication of the importance of the glutathione redox cycle in protecting against endothelial damage induced by H2O2. Catalase also protects the tissues bordering the anterior chamber from H2O2-induced damage. Decreasing catalase activity by treatment with 3-aminotriazole increases the time required for H2O2 clearance from the anterior chamber, thereby allowing more time for H2O2 to produce damage. A decline of catalase activity with age has been observed in the iris and corneal endothelium of rabbits.
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PMID:Physiologic neutralization mechanisms and the response of the corneal endothelium to hydrogen peroxide. 240 81

The effects of 60 min hypoxia and subsequent reoxygenation for 30 min on enzymatic (NADPH-dependent) and nonenzymatic (Fe2+/ascorbate-induced) lipid peroxidation capacities and on antioxidant levels were studied using Langendorff-perfused rat hearts. The assays were done on the myolayer of the right ventricle (RV) and on the subepi- and subendomyolayers of the left ventricle (epi/endo LV) after normoxic, hypoxic, and reoxygenation phases. The region injured by hypoxia/reoxygenation was located mainly in endo LV, seen as a lesser penetration of the fluorescent dye fluorescein in the myocardium. The electron microscopic findings after reoxygenation revealed swelling of the mitochondria, amorphous mitochondrial structures, and formation of paracrystallines. The myofibrillar structure of the cells was disrupted and the cells showed marked fluid accumulation. Membrane structures were marginated and formed blebs and multilamellar bodies. Ultrastructural changes were most prominent in endo LV, especially after reoxygenation. The increase in leakage of lactate in the perfusate revealed the onset of anaerobic metabolism. Abrupt release of the cytoplasmic enzymes lactate dehydrogenase and creatine kinase at the beginning of the reoxygenation phase suggested cell membrane injury. The capacity for Fe2+/ascorbate-induced lipid peroxidation slightly increased in RV and that for NADPH-dependent, enzymatic lipid peroxidation in endo LV after reoxygenation. Catalase, glutathione peroxidase, and superoxide dismutase activities remained unchanged, whereas glucose-6-phosphate dehydrogenase activity decreased after reoxygenation in RV.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzymatic and nonenzymatic lipid peroxidation capacities and antioxidants in hypoxic and reoxygenated rat myocardium. 270 86

Multiple lines of evidence show that oxidation products of ascorbic acid (vitamin C) are capable of inducing a variety of genetic alterations in microbial and mammalian cells. We have studied the inactivation kinetics in repair proficient and deficient Escherichia coli K12 cells treated with oxidized solutions of ascorbic acid, in the presence of catalytic amounts of copper. Our results suggest that the repair pathways controlled by the recA and uvrA gene products (the latter in a recA strain) contribute to cell survival. However, the lack of beta-galactosidase induction, in the SOS chromotest, implies a role for the RecA protein other than SOS induction. Catalase and thiourea suppress the toxic effects of oxidized ascorbate solutions, confirming that H2O2 and hydroxyl radicals are intermediate agents in the damaging action. Single-strand breaks were detected in DNA from treated cells.
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PMID:Ascorbate-copper induced DNA lesions and repair in Escherichia coli K12 cells. 300 73

The effect of complex formation between ferricytochrome c and cytochrome c peroxidase (Ferrocytochrome-c:hydrogen peroxide oxidoreductase, EC 1.11.1.5) on the reduction of cytochrome c by N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), reduced N-methylphenazonium methosulfate (PMSH), and ascorbate has been determined at low ionic strength (pH 7) and 25 degrees C. Complex formation with the peroxidase enhances the rate of ferricytochrome c reduction by the neutral reductants TMPD and PMSH. Under all experimental conditions investigated, complex formation with cytochrome c peroxidase inhibits the ascorbate reduction of ferricytochrome c. This inhibition is due to the unfavorable electrostatic interactions between the ascorbate dianion and the negatively charged cytochrome c-cytochrome c peroxidase complex. Corrections for the electrostatic term by extrapolating the data to infinite ionic strength suggest that ascorbate can reduce cytochrome c peroxidase-bound cytochrome c faster than free cytochrome c. Reduction of cytochrome c peroxidase Compound II by dicyanobis(1,10-phenanthroline)iron(II) (Fe(phen)2(CN)2) is essentially unaffected by complex formation between the enzyme and ferricytochrome c at low ionic strength (pH 6) and 25 degrees C. However, reduction of Compound II by the negatively changed tetracyano-(1,10-phenanthroline)iron(II) (Fe(phen)(CN)4) is enhanced in the presence of ferricytochrome c. This enhancement is due to the more favorable electrostatic interactions between the reductant and cytochrome c-cytochrome c peroxidase Compound II complex then for Compound II itself. These studies indicate that complex formation between cytochrome c and cytochrome c peroxidase does not sterically block the electron-transfer pathways from these small nonphysiological reductants to the hemes in these two proteins.
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PMID:The effect of complex formation upon the reduction rates of cytochrome c and cytochrome c peroxidase compound II. 303 33

The enzymes involved in antioxidative activity and the cellular content of the antioxidants glutathione and ascorbate in the cyanobacteria Nostoc muscorum 7119 and Synechococcus 6311 have been examined for their roles in hydroperoxide removal. High activities of ascorbate peroxidase and catalase were found in vegetative cells of both species and in the heterocysts of N. muscorum. The affinity of ascorbate peroxidase for H2O2 was 15- to 25-fold higher than that of catalase. Increased activity of ascorbate peroxidase was observed in N. muscorum when H2O2 production was enhanced by photorespiration. Catalase activity was decreased in dilute cultures whereas ascorbate peroxidase activity increased. Ascorbate peroxidase activity also increased when the CO2 concentration was reduced. Ascorbate peroxidase appears to be a key enzyme in a cascade of reactions regenerating antioxidants. Dehydroascorbate reductase was found to regenerate ascorbate, and glutathione reductase recycled glutathione. In vegetative cells glutathione was present in high amounts (2-4 mM) whereas the ascorbate content was almost 100-fold lower (20-100 microM). Glutathione peroxidase was not detected in either cyanobacterium. It is concluded from the high activity of ascorbate peroxidase activity and the levels of antioxidants found that this enzyme can effectively remove low concentrations of peroxides. Catalase may remove H2O2 produced under photooxidative conditions where the peroxide concentration is higher.
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PMID:Hydroperoxide metabolism in cyanobacteria. 308 78

This study examined the effects of gossypol acetic acid on the antioxidant defense system of the rat testis. In gossypol-treated animals testis catalase and glutathione peroxidase activities were decreased. Catalase and glutathione peroxidase are the two enzymes that protect against oxidative damage by hydrogen peroxide. Other antioxidants that were reduced in treated animals were glucose-6-phosphate dehydrogenase, superoxide dismutase, glutathione reductase, alpha-tocopherol, and ascorbate. Gossypol, a pigment of cottonseed and cottonseed products, causes infertility in humans and many animal species, but its mechanism of action is unknown. Gossypol is known to produce reactive oxygen species in vitro. Oxidative injury caused by the generation of reactive oxygen species and a compromised antioxidant defense system may be responsible for the antifertility effects of gossypol.
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PMID:Effects of gossypol on the antioxidant defense system of the rat testis. 319 Mar 61

In the presence of intact Ehrlich ascite carcinoma cells and the supernatant obtained by preincubation and subsequent precipitation of cells, egg phosphatidylcholine is oxidized in liposomes to form malonic dialdehyde (MDA). Catalase and carbon dioxide markedly reduce, whereas sodium azide increases MDA accumulation during liposome incubation with the cells. EDTA, diethylthiocarbonate and alpha-tocopherol effectively inhibit, whereas ascorbate and cysteine strongly activate MDA synthesis in both cases. Superoxide dismutase has no appreciable effect on these processes. It is concluded that metal-containing catalysts and the H2O2 released by intact cells into the incubation medium induce lipid peroxidation in liposomes.
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PMID:[Mechanism of formation of malonic dialdehyde during liposome interaction with cells]. 320 6

The addition of luminol plus a catalyst such as peroxidase or a heme prosthetic group to a solution containing a small quantity of lipid hydroperoxides results in a flash of chemiluminescence, the intensity of which is a function of the hydroperoxide concentrations. Various protocols for lipid hydroperoxide assays have been described and we have studied conditions to increase their sensitivity and specificity. Plasma lipid hydroperoxide determinations require an extraction, since compounds present in plasma interfere with light emission. Moreover, the sensitivity of the assay is by the presence of hydrogen peroxide in the medium, which causes high background values. Catalase does not act on lipid hydroperoxides and can be used to eliminate hydrogen peroxide from the reaction medium. The determination requires a blank tube in which hydroperoxides are destroyed by incubating the sample with haematin plus ascorbate. The increase in the chemiluminescence of the assay tube caused by the presence of lipid hydroperoxides is then compared to the value obtained for an internal standard.
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PMID:Chemiluminescent assay of lipid hydroperoxides. 321 96


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