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Query: UNIPROT:P04040 (
Catalase
)
3,577
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Human blood platelets produce oxidant species when stimulated by collagen and thrombin. The oxidative burst of platelets has been studied by cytofluorimetry taking advantage of the fluorogenic dye DCFH2-DA, which is taken up and deacetylated by platelets and then oxidized to the fluorescent derivative
DCF
. The oxidation of DCFH2 is induced by stimulation with collagen but not with thrombin and inhibited by external catalase.
Catalase
also inhibited the aggregation induced by collagen, but not that induced by thrombin. Aspirin and indomethacin inhibited the formation of the fluorochrome only when platelets were stimulated by thrombin. Externally added H2O2 increased the cytoplasmic calcium content as probed by the fluorescence of Indo-1. The present data suggest that collagen induces the production of H2O2, which in turn may stimulate the aggregation of platelets through a calcium mobilization. Instead the stimulation by thrombin does not require the intermediacy of H2O2.
...
PMID:Hydrogen peroxide is an intermediate in the platelet activation cascade triggered by collagen, but not by thrombin. 189 57
The oxidation of 2',7'-dichlorofluorescin (DCFH) and its diacetate form (DCFHDA) by the HRP/peroxynitrite system was investigated. Both DCFH and DCFHDA were oxidized to fluorescent products. A major anomaly, however, was the observation that fluorescence continued to build up long after peroxynitrite total decomposition and the initial HRP compound I reduction, suggesting the production of oxidants by the system. Indeed, preformed HRP compound I was instantly reduced by DCFH and DCFHDA to compound II with the obligate formation of
DCF
(-) semiquinone and DCFHDA-derived radicals.
Catalase
strongly inhibited fluorescence and EPR signals, suggesting the intermediate formation of H2O2. Taken together the data indicate that peroxynitrite rapidly oxidizes HRP to HRP compound I, which is reduced by DCFH and its diacetate form with the concomitant formation of
DCF
(-) semiquinone and DCFHDA-derived radicals. These are oxidized by O2, producing O2(-) (as demonstrated by EPR and oxygen consumption experiments), which dismutates to produce H2O2, which serves to fuel further DCFH/DCFHDA oxidation via HRP catalysis. Also DCFHDA was shown to be considerably more resistant to oxidation than its hydrolyzed product DCFH, presumably because of the absence of the easily oxidizable phenol moieties. DCFHDA/DCFH have been used to study free radical production in a variety of systems. Our findings demonstrate that this assay is subject to a serious artifact in that it produces what it is purported to measure; therefore, its use in biological systems should be approached with caution.
...
PMID:The oxidation of 2',7'-dichlorofluorescin to reactive oxygen species: a self-fulfilling prophesy? 1654 Mar 92
Oxidative stress is a hallmark of asthma, and increased levels of oxidants are considered markers of the inflammatory process. Most studies to date addressing the role of oxidants in the etiology of asthma were based on the therapeutic administration of low m.w. antioxidants or antioxidant mimetic compounds. To directly address the function of endogenous hydrogen peroxide in the pathophysiology of allergic airway disease, we comparatively evaluated mice systemically overexpressing catalase, a major antioxidant enzyme that detoxifies hydrogen peroxide, and C57BL/6 strain matched controls in the OVA model of allergic airways disease.
Catalase
transgenic mice had 8-fold increases in catalase activity in lung tissue, and had lowered
DCF
oxidation in tracheal epithelial cells, compared with C57BL/6 controls. Despite these differences, both strains showed similar increases in OVA-specific IgE, IgG1, and IgG2a levels, comparable airway and tissue inflammation, and identical increases in procollagen 1 mRNA expression, following sensitization and challenge with OVA. Unexpectedly, mRNA expression of MUC5AC and CLCA3 genes were enhanced in catalase transgenic mice, compared with C57BL/6 mice subjected to Ag. Furthermore, when compared with control mice, catalase overexpression increased airway hyperresponsiveness to methacholine both in naive mice as well as in response to Ag. In contrast to the prevailing notion that hydrogen peroxide is positively associated with the etiology of allergic airways disease, the current findings suggest that endogenous hydrogen peroxide serves a role in suppressing both mucus production and airway hyperresponsiveness.
...
PMID:Catalase overexpression fails to attenuate allergic airways disease in the mouse. 1733 80
After operative restoration, some monomers released from dentin bonding agents or composite resin may induce tissue inflammation and affect the vitality of dental pulp. Whether BisGMA, a major monomer of composite resin, may induce prostaglandin release and cytotoxicity to pulp cells and their mechanisms awaits investigation. We found that BisGMA induced cytotoxicity to human dental pulp cells at concentrations higher than 0.075 mm as analyzed by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. BisGMA (0.1 mm) also stimulated ERK phosphorylation, PGE(2) production, COX-2 mRNA and protein expression as well as ROS production (as indicated by an increase in cellular
DCF
fluorescence) in dental pulp cells.
Catalase
(500 and 1000 U/ml) and U0126 (10 and 20 microm, a MEK inhibitor) effectively prevented the BisGMA-induced ERK activation, PGE(2) production and COX-2 expression. Moreover, catalase can protect the pulp cells from BisGMA cytotoxicity, whereas aspirin and U0126 lacked of this protective activity. These results suggest that BisGMA released from composite resin may potentially affect the vitality of dental pulp and induce pulpal inflammation via stimulation of ROS production, MEK/ERK1/2 activation and subsequent COX-2 gene expression and PGE(2) production. Cytotoxicity of BisGMA to dental pulp cells is related to ROS production, but not directly mediated by MEK activation and PGE(2) production.
...
PMID:The effect of BisGMA on cyclooxygenase-2 expression, PGE2 production and cytotoxicity via reactive oxygen species- and MEK/ERK-dependent and -independent pathways. 1946 1
Catalase
is well-known as an antioxidant dismutating H
2
O
2
to O
2
and H
2
O. However, catalases evolved when metabolism was largely sulfur-based, long before O
2
and reactive oxygen species (ROS) became abundant, suggesting catalase metabolizes reactive sulfide species (RSS). Here we examine catalase metabolism of H
2
S
n
, the sulfur analog of H
2
O
2
, hydrogen sulfide (H
2
S) and other sulfur-bearing molecules using H
2
S-specific amperometric electrodes and fluorophores to measure polysulfides (H
2
S
n
; SSP4) and ROS (dichlorofluorescein,
DCF
).
Catalase
eliminated H
2
S
n
, but did not anaerobically generate H
2
S, the expected product of dismutation. Instead, catalase concentration- and oxygen-dependently metabolized H
2
S and in so doing acted as a sulfide oxidase with a P
50
of 20mmHg. H
2
O
2
had little effect on catalase-mediated H
2
S metabolism but in the presence of the catalase inhibitor, sodium azide (Az), H
2
O
2
rapidly and efficiently expedited H
2
S metabolism in both normoxia and hypoxia suggesting H
2
O
2
is an effective electron acceptor in this reaction. Unexpectedly, catalase concentration-dependently generated H
2
S from dithiothreitol (DTT) in both normoxia and hypoxia, concomitantly oxidizing H
2
S in the presence of O
2
. H
2
S production from DTT was inhibited by carbon monoxide and augmented by NADPH suggesting that catalase heme-iron is the catalytic site and that NADPH provides reducing equivalents.
Catalase
also generated H
2
S from garlic oil, diallyltrisulfide, thioredoxin and sulfur dioxide, but not from sulfite, metabisulfite, carbonyl sulfide, cysteine, cystine, glutathione or oxidized glutathione. Oxidase activity was also present in catalase from Aspergillus niger. These results show that catalase can act as either a sulfide oxidase or sulfur reductase and they suggest that these activities likely played a prominent role in sulfur metabolism during evolution and may continue do so in modern cells as well. This also appears to be the first observation of catalase reductase activity independent of peroxide dismutation.
...
PMID:Catalase as a sulfide-sulfur oxido-reductase: An ancient (and modern?) regulator of reactive sulfur species (RSS). 2836 63
Fluorescence spectroscopy and microscopy have been used extensively to monitor biomolecules, especially reactive oxygen species (ROS) and, more recently, reactive sulfide (RSS) species. Nearly all fluorophores are either excited by or emit light between 450 and 550 nm, which is similar to the absorbance of heme proteins and metal-centered porphyrins. Here we examined the effects of catalase (Cat), reduced and oxidized hemoglobin (Hb and metHb), albumin (alb), manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP), iron protoporphyrin IX (hemin), and copper protoporphyrin IX (CuPPIX) on the fluorescence properties of fluorescein. We also examined the effects of catalase and MnTBAP on fluorophores for ROS (dichlorofluorescein,
DCF
), polysulfides (3',6'-di(
O
-thiosalicyl)fluorescein, SSP4), and H
2
S (7-azido-4-methylcoumarin, AzMC) previously activated by H
2
O
2
, a mixed polysulfide (H
2
S
n
,
n
= 1-7) and H
2
S, respectively. All except albumin concentration dependently inhibited fluorophore fluorescence and absorbed light between 450 and 550 nm, suggesting that the inhibitory effect was physical not catalytic.
Catalase
inhibition of fluorescein fluorescence was unaffected by sodium azide, dithiothreitol, diamide, tris(2-carboxyethyl)phosphine (TCEP), or iodoacetate, supporting a physical inhibitory mechanism.
Catalase
and TBAP augmented, then inhibited
DCF
fluorescence, but only inhibited SSP4 and AzMC fluorescence indicative of a substrate-specific catalytic oxidation of
DCF
and nonspecific fluorescence inhibition of all three fluorophores. These results suggest caution must be exercised when using any fluorescent tracers in the vicinity of metal-centered porphyrins.
...
PMID:Fluorescence quenching by metal centered porphyrins and poryphyrin enzymes. 2883 49
