Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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

Benzene is a widely recognized human carcinogen. The mechanism of DNA damage induced by major benzene metabolites 1,4-benzoquinone (1,4-BQ) and hydroquinone (1,4-HQ) was investigated in relation to apoptosis and carcinogenesis. Pulsed-field gel electrophoresis showed that cellular DNA strand breakage was induced by benzene metabolites. Internucleosomal DNA fragmentation and morphological changes of apoptotic cells were observed at higher concentrations of benzene metabolites. Flow cytometry showed an increase of peroxides in cultured cells treated with benzene metabolites. 1,4-BQ induced these changes at a much lower concentration than 1,4-HQ. Damage to DNA fragments obtained from the c-Ha-ras-1 proto-oncogene was investigated by a DNA sequencing technique. 1,4-BQ + NADH and 1,4-HQ induced piperidine-labile sites frequently at thymine residues in the presence of Cu(II). Catalase and bathocuproine inhibited DNA damage, suggesting that H2O2 reacts with Cu(I) to produce active species causing DNA damage. Electron spin resonance studies showed that semiquinone radical was produced by NADH-mediated reduction of 1,4-BQ and autoxidation of 1,4-HQ, suggesting that benzene metabolites produce O2- and H2O2 via the formation of semiquinone radical. These results suggest that these benzene metabolites cause DNA damage through H2O2 generation in cells, preceding internucleosomal DNA fragmentation leading to apoptosis. The fates of the cells to apoptosis or mutation might be dependent on the intensity of DNA damage and the ability to repair DNA.
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PMID:Oxidative DNA damage and apoptosis induced by benzene metabolites. 891 53

Catalase activity in cell cultures of fetal rat mesencephalon was decreased by 42 and 50%, respectively, after exposure to L-3,4-dihydroxyphenylalanine (L-DOPA, 100 microM) or dopamine (100 microM) for 48 h. Catalase activity was also decreased 21% by 10 microM hydroquinone. Ascorbic acid (200 microM), an agent that suppresses the autoxidation of L-DOPA and dopamine, blocked the anti-catalase effect of L-DOPA, but not that of dopamine. Inhibitors of the A and B forms of monoamine oxidase (20 microM clorgyline plus 20 microM pargyline) had no effect on the anti-catalase action of either L-DOPA or dopamine. The latter results suggest that products of the oxidative deamination of dopamine by monoamine oxidase are not involved in the suppression of catalase activity. However, autoxidation reactions of L-DOPA may play a role since ascorbate suppressed the anti-catalase effect of L-DOPA. On the contrary, the basis for the failure of ascorbate to similarly block the anti-catalase effect of dopamine is uncertain. L-DOPA and dopamine (25 microM) also inhibited crystalline catalase in solution after incubation for 1 h at neutral pH (40-50% inhibition). Inhibition was blocked by 0.45 M ethanol, indicating a need for autoxidation and the formation of compound II, which is an enzymatically inactive form of catalase. The ability to model the enzyme inhibition in purely chemical experiments indicates a probable mechanism for loss of enzymatic activity in cell cultures. Inhibition of catalase may contribute to cell damage during incubation of cultures with L-DOPA, dopamine, or other autoxidizable compounds.
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PMID:Inhibition of catalase in mesencephalic cultures by L-DOPA and dopamine. 911 32

Previously, we have shown that aqueous cigarette tar (ACT) extracts contain a long-lived tar radical that associates with DNA in isolated rat alveolar macrophages and causes DNA damage in isolated rat thymocytes. These ACT solutions reduce oxygen to produce superoxide and, ultimately, hydrogen peroxide. In this study, we report the fractionation of ACT solutions prepared from the tar from five cigarettes using Sephadex columns. The fractions were analyzed by UV and electron paramagnetic resonance (EPR) spectroscopy and gas chromatography/mass spectrometry (GC/MS). The fractions containing polyphenolic species (principally catechol and hydroquinone, as determined by MS) caused most of the observed DNA damage in rat thymocytes. These DNA-damaging fractions produced superoxide, H2O2, and hydroxyl radicals. Stable free radicals were identified as o- and p-benzosemiquinone radicals by EPR spectroscopy. Hydroxyl radicals were detected by EPR spin-trapping with 5, 5-dimethyl-1-pyrroline N-oxide (DMPO). Catalase inhibited the EPR signal of the DMPO-OH adduct, indicating that H2O2 is the precursor of the hydroxyl radical spin adduct. The Sephadex separation resulted in a 90-fold concentration of the hydrogen peroxide-generating capacity of the fractions that contained polyphenols, relative to the unfractionated ACT solution. Another fraction, which contained nicotine, caused some DNA damage, but this damage was 28-fold less than the damage caused by the most damaging phenolic fraction. These results support our hypothesis that the tar radical system is an equilibrium mixture of semiquinones, hydroquinones, and quinones. The tar radical associates with DNA, causes DNA damage, and very likely is involved in the toxicity associated with cigarette smoking.
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PMID:Fractionation of aqueous cigarette tar extracts: fractions that contain the tar radical cause DNA damage. 958 74

In low concentrations, benzene and its metabolite hydroquinone are known to have diverse biological effects on cells, including the synergistic stimulation with GM-CSF of hematopoietic colony formation in vitro, stimulation of granulocytic differentiation in vitro and in vivo, and general suppression of hematopoiesis in vivo. These chemicals are also known to be active in the induction of active oxygen species. We used several assays to determine the effects of benzene metabolites (hydroquinone, benzenetriol, benzoquinone) and active oxygen species (xanthine/xanthine oxidase) on cell growth and cell cycle kinetics of the human myeloid cell line HL-60. HL-60 cells treated with these chemicals for 2 h in PBS showed increased growth over untreated controls in a subsequent 18h growth period in complete media. Incorporation of 3H-thymidine was also increased proportionately by these treatments. Catalase treatment abrogated the increased cell growth of all chemicals, suggesting an oxidative mechanism for the effect of all treatments alike. Cell cycle kinetics assays showed that the growth increase was caused by an increased recruitment of cells from G0/G1 to S-phase for both hydroquinone and active oxygen, rather than a decrease in the length of the cell cycle. Benzene metabolite's enhancement of growth of myeloid cells through an active oxygen mechanism may be involved in a number of aspects of benzene toxicity, including enhanced granulocytic growth and differentiation, stimulation of GM-CSF-induced colony formation, apoptosis inhibition, and stimulation of progenitor cell mitogenesis in the bone marrow. These effects in sum may be involved in the benzene-induced "promotion" of a clonal cell population to the fully leukemic state.
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PMID:Enhancement of myeloid cell growth by benzene metabolites via the production of active oxygen species. 1019 77

Polyphenols in several oxidation systems gained amine oxidase-like activity, probably due to the formation of the corresponding quinones. In the presence of Cu(II), o- and p-phenolic compounds exhibited amine oxidase-like activity, whereas only the o-phenolic compounds showed the activity in the presence of 1,1-diphenyl-2-picrylhydrazyl radical. The activity was determined by measuring the conversion of benzylamine to benzaldehyde by HPLC. Moreover, gallic acid, chlorogenic acid, and caffeic acid, which are plant polyphenols, converted the lysine residue of bovine serum albumin to alpha-amino-adipic semialdehyde residue, indicating lysyl oxidase-like activity. We also characterized the activity of pyrocatechol, hydroquinone, and pyrogallol in the presence of Cu(II). The oxidative deamination was accelerated at a higher pH, and required O2 and transition metal ions. Furthermore, EDTA markedly inhibited the reaction but not beta-aminopropionitrile, which is a specific inhibitor of lysyl oxidase. Catalase significantly inhibited the oxidation, implying the participation of hydroxyl radical in the reaction, but superoxide dismutase stimulated the oxidation, probably due to its radical formation activity. We discussed the mechanism of the oxidative deamination by polyphenols and the possible significance of the activity for biological systems.
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PMID:Amine oxidase-like activity of polyphenols. Mechanism and properties. 1127 17

2,3,5-Tris(glutathion-S-yl)hydroquinone [TGHQ] is a potent nephrotoxicant and nephrocarcinogen, and induces a spectrum of mutations in human and bacterial cells consistent with those attributed to reactive oxygen species (ROS). Studies were conducted to determine whether the oxidative stress induced by TGHQ in renal proximal tubule epithelial cells (LLC-PK(1)) modulates transcriptional activities widely implicated in transformation responses, namely 12-O-tetradecanoyl phorbol 13-acetate (TPA) responsive element (TRE)- and nuclear factor kappa B (NF-kappaB)-binding activity. TGHQ increased TRE- and NF-kappaB-binding activity in a concentration- and time-dependent manner. Catalase fully inhibited peak TGHQ-mediated TRE- and NF-kappaB-binding activity. In contrast, although deferoxamine fully inhibited TGHQ-mediated TRE-binding activity, it had only a marginal effect on NF-kappaB-binding activity. Collectively, these data indicate that TGHQ modulates TRE- and NF-kappaB-binding activity in an ROS-dependent fashion. Cycloheximide and actinomycin D fully inhibited TGHQ-mediated TRE-binding activity, but in the absence of TGHQ increased NF-kappaB-binding activity. Although protein kinase C (PKC) is widely implicated in stress response signaling, pretreatment of cells with PKC inhibitors (H-89, calphostin C) did not modulate TGHQ-mediated DNA-binding activities. In contrast, pretreatment of cells with (PD098059), a mitogen activated protein kinase kinase (MEK) inhibitor, markedly reduced TGHQ-mediated TRE-binding activity, but enhanced TGHQ-mediated NF-kappaB-binding activity. We conclude that TGHQ-mediated TRE- and NF-kappaB-binding activities are ROS-dependent. Although there is a common requirement for hydrogen peroxide (H(2)O(2)) in the regulation of these DNA-binding activities, there appears to be divergent regulation after H(2)O(2) generation in renal epithelial cells.
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PMID:Differential regulation of redox responsive transcription factors by the nephrocarcinogen 2,3,5-Tris(glutathion-S-yl)hydroquinone. 1145 27

The redox cycle of 2,5-dimethoxybenzoquinone (2,5-DMBQ) is proposed as a source of reducing equivalent for the regeneration of Fe2+ and H2O2 in brown rot fungal decay of wood. Oxalate has also been proposed to be the physiological iron reductant. We characterized the effect of pH and oxalate on the 2,5-DMBQ-driven Fenton chemistry and on Fe3+ reduction and oxidation. Hydroxyl radical formation was assessed by lipid peroxidation. We found that hydroquinone (2,5-DMHQ) is very stable in the absence of iron at pH 2 to 4, the pH of degraded wood. 2,5-DMHQ readily reduces Fe3+ at a rate constant of 4.5 x 10(3) M(-1)s(-1) at pH 4.0. Fe2+ is also very stable at a low pH. H2O2 generation results from the autoxidation of the semiquinone radical and was observed only when 2,5-DMHQ was incubated with Fe3+. Consistent with this conclusion, lipid peroxidation occurred only in incubation mixtures containing both 2,5-DMHQ and Fe3+. Catalase and hydroxyl radical scavengers were effective inhibitors of lipid peroxidation, whereas superoxide dismutase caused no inhibition. At a low concentration of oxalate (50 micro M), ferric ion reduction and lipid peroxidation are enhanced. Thus, the enhancement of both ferric ion reduction and lipid peroxidation may be due to oxalate increasing the solubility of the ferric ion. Increasing the oxalate concentration such that the oxalate/ferric ion ratio favored formation of the 2:1 and 3:1 complexes resulted in inhibition of iron reduction and lipid peroxidation. Our results confirm that hydroxyl radical formation occurs via the 2,5-DMBQ redox cycle.
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PMID:Effect of pH and oxalate on hydroquinone-derived hydroxyl radical formation during brown rot wood degradation. 1453 58

A sensitive hydrogen peroxidase (H2O2) amperometric sensor based on horseradish peroxidase (HRP)-labeled nano-Au colloids has been proposed. Nano-Au colloids were immobilized by the thiol group of cysteamine, which was associated with the carboxyl groups of poly(2,6-pyridinedicarboxylic acid) (PPDA). With the aid of the hydroquinone, the sensor displayed excellent electrocatalytical response to the reduction of H2O2. Compared with the non-Au-colloid modified electrode, i.e., PPDA/HRP, the Au-colloid modified electrode exhibited better performance characteristics, including stability, reproducibility, sensitivity and accuracy. The biosensor shows a linear response to H2O2 in the range of 3.0 x 10(-7) - 2 x 10(-3) M. The detection limit was 1.0 x 10(-7) M.
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PMID:Amperometric hydrogen peroxide biosensor based on horseradish peroxidase-labeled nano-Au colloids immobilized on poly(2,6-pyridinedicarboxylic acid) layer by cysteamine. 1547 36

The ability to monitor hydrogen peroxide (H2O2) in aqueous smoke extracts will advance our understanding of the relationship between cigarette smoke-induced oxidative stress, inflammation, and disease and help elucidate the pathways by which the various smoke constituents exert their pathogenic effects. We have demonstrated, for the first time, the measurement of H2O2 production from cigarette smoke without prior separation of the sample. Cigarettes were tested on a commercial smoking machine, such that the whole smoke or gas vapor phase was bubbled through phosphate buffered saline solution at pH 7.4. Aliquots of these solutions were analyzed using an Amplex Red/horseradish peroxidase fluorimetric assay that required only a 2 minute incubation time, facilitating the rapid, facile collection of data. Catalase was used to demonstrate the selectivity and specificity of the assay for H2O2 in the complex smoke matrix. We measured approximately 7-8 microM H2O2 from two reference cigarettes (i.e., 1R4F and 2R4F). We also observed 9x more H2O2 from whole smoke bubbled samples compared to the gas vapor phase, indicating that the major constituent(s) responsible for H2O2 formation reside in the particulate phase of cigarette smoke. Aqueous solutions of hydroquinone and catechol, both of which are particulate phase constituents of cigarette smoke, generated no H2O2 even though they are free radical precursors involved in the production of reactive oxygen species in the smoke matrix.
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PMID:Near-real-time determination of hydrogen peroxide generated from cigarette smoke. 1598 47

Root and stem segments from soybean (Merrill cv. ;Bragg') showed an enhanced chemiluminescence upon mechanical injury. Roots emitted more light than did stems. Light emission was diminished by CN(-) and N(3) (-) but was not affected by rotenone and antimycin A. Catalase quenched chemiluminescence in wounded root segments as did ascorbic acid and hydroquinone. Superoxide dismutase addition resulted in a small diminution in light emission, but mannitol, an OH. scavenger, was without effect. The addition of H(2)O(2) to wounded root segments markedly elevated chemiluminescence in the presence of air as well as under N(2). It is concluded that peroxidases, found abundantly in roots, predominantly contribute to light emission in wounded plant tissue.
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PMID:Chemiluminescence in Wounded Root Tissue : EVIDENCE FOR PEROXIDASE INVOLVEMENT. 1666 30


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