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

The role of oxygen-derived free radicals (ODFR) in lectin-dependent cellular cytotoxicity (LDCC) in humans was investigated. The hydroxyl radical traps thiourea, methanol, ethanol and phenol were effective in inhibiting LDCC, as was DABCO, a singlet oxygen quencher. The proposed pathway of hydroxyl radical production in living cells is either an iron catalysed Haber-Weiss reaction or a Fenton reaction. The effect of inhibitors of these pathways was investigated. The superoxide anion scavengers superoxide dismutase, ferricytochrome c and Tiron were without effect. It was shown that Tiron inhibits the lucigenin-amplified chemiluminescence produced by the action of xanthine oxidase, and also the lucigenin-amplified chemiluminescence produced by activated PMN, suggesting that this agent (Tiron) scavenges intracellular superoxide anion. Catalase gave slight inhibition of LDCC only. The ferric iron chelator desferrioxamine gave no protection of the target cells, while the ferrous chelator, 1,10-phenanthroline, inhibited LDCC and partially prevented the detection of hydroxyl radicals generated by the Fe2+-H2O2 system. Cibacron blue, an agent that inhibits NAD(P)H linked enzymes, also inhibited LDCC. The cyclo-oxygenase inhibitors indomethacin and salicylate were without effect, while the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) inhibited cytolysis. None of the LDCC inhibitors was cytotoxic to the effector cells or to the target cells, neither did they inhibit lymphocyte-target binding. The findings would suggest that hydroxyl radicals have a role to play in human T-cell mediated cytolysis, either as the active lytic agent or as an epiphenomenon.
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PMID:Hydroxyl radical scavengers inhibit human lectin-dependent cellular cytotoxicity. 301 54

Catalase (hydroperoxidase II or HPII) of Escherichia coli K12 has been purified using a protocol that also allows the purification of the second catalase HPI in large amounts. The purified HPII was found to have equal amounts of two subunits with molecular weights of 90,000 and 92,000. Only a single 92,000 subunit was present in the immunoprecipitate created when HPII antiserum was added directly to a crude extract, suggesting that proteolysis was responsible for the smaller subunit. The apparent native molecular weight was determined to be 532,000, suggesting a hexamer structure for the enzyme, an unusual structure for a catalase. HPII was very stable, remaining maximally active over the pH range 4-11 and retaining activity even in a solution of 0.1% sodium dodecyl sulfate and 7 M urea. The heme cofactor associated with HPII was also unusual for a catalase, in resembling heme d (a2) both spectrally and in terms of solubility. On the basis of heme-associated iron, six heme groups were associated with each molecule of enzyme or one per subunit.
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PMID:Purification and characterization of catalase HPII from Escherichia coli K12. 301 70

The potential for iron bound to transferrin to be released and promote the peroxidation of phospholipid liposomes was investigated using ADP as a low molecular weight chelator and superoxide generated by the xanthine/xanthine oxidase system as the reducing agent. Lipid peroxidation in this system was dependent upon transferrin as the source of iron; increasing the transferrin concentration resulted in increased rates of lipid peroxidation. Increasing the xanthine oxidase activity also caused increased rates of peroxidation. Catalase stimulated rates of peroxidation at all xanthine oxidase activities tested. Conditions resulting in the most rapid release of iron from transferrin (low pH, high ADP) did not promote the greatest rates of lipid peroxidation, indicating that at neutral pH, rates of lipid peroxidation may be limited by the availability of iron. It is concluded that transferrin is not a likely source of iron for catalysis of deleterious biological oxidations such as lipid peroxidation in vivo.
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PMID:Transferrin-dependent lipid peroxidation. 302 12

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

Chronic inflammatory synovitis is characterized by both lymphocytic infiltrates and persistent polymorph exudates. Activated polymorphs release reactive oxygen species (ROS) during inflammation, but the contribution that these make to the lymphocyte abnormalities associated with RA has been little studied. We therefore investigated the cytotoxic effects of the reactive oxygen species on human peripheral blood mononuclear cells (PBMC). PBMC were exposed to RPMI 1640 medium previously irradiated for up to 60 min. Consistent dose-dependent killing was observed at 24 h. Antioxidant studies indicated that H2O2 was the effective species. Catalase, which specifically degrades H2O2, gave almost total protection against cell death, while superoxide dismutase (SOD), thiourea, and mannitol were largely ineffective. Addition of exogenous H2O2 caused an identical pattern of cell death to that observed with irradiated medium. PBMC cultures supplemented with desferrioxamine (a ferric iron chelator) also gave significant protection, suggesting that H2O2 mediated its effects via OH radicals. Analysis of lymphocyte subpopulations showed that ROS caused a selective depletion, depending on the level of H2O2 present. Low levels induced a specific loss of CD8+ cells, while higher concentrations caused significant loss of CD4+ T cells as well. sIg+ B cells were unaffected at either concentration. This selective lymphotoxic effect of ROS may be of considerable importance in the pathogenesis of autoimmune inflammatory disease.
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PMID:Reactive oxygen species selectively deplete normal T lymphocytes via a hydroxyl radical dependent mechanism. 303 50

Bactericidal effects of polyunsaturated fatty acids were investigated by using an in vitro killing assay. All gram-positive species tested were extremely susceptible to 10(-5) M arachidonic acid as were Neisseria, Branhamella, and Haemophilus spp. Pseudomonas aeruginosa and and members of the Enterobacteriaceae were resistant. The toxicity of polyunsaturated fatty acids for Staphylococcus aureus was dependent upon time, concentration, and fatty acid unsaturation. Arachidonic acid underwent peroxidation when incubated with S. aureus, but arachidonic acid peroxidation products had low bactericidal activity. Catalase protected S. aureus, whereas superoxide dismutase was ineffective. Scavengers of hydroxyl radicals or singlet oxygen or removal of halide ions had little effect on arachidonic acid-induced killing of bacteria, whereas transition metal chelators and some thiols were highly protective. S. aureus grown in iron-supplemented broth had increased iron content and arachidonic acid susceptibility. Ascorbate also potentiated arachidonic acid-induced killing of S. aureus. These observations indicate that bactericidal effects of polyunsaturated fatty acids are mediated by a peroxidative process involving H2O2 and bacterial iron.
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PMID:Bactericidal effects of polyunsaturated fatty acids. 308 65

Reactive oxygen metabolites have been reported to be responsible for the pathogenesis of ischemia-induced gastric mucosal lesions. We have investigated the possible protective effect of specific enzymes and oxygen radical scavenging agents on oxygen metabolite-induced injury to cultured gastric mucosal cells. Oxygen-reactive metabolites were generated by 1 mM xanthine and 10-100 mU/ml xanthine oxidase. Cytotoxicity was quantified by measuring 51Cr release from prelabeled cells. Xanthine oxidase caused a dose-dependent increase of 51Cr release in the presence of 1 mM xanthine. Catalase (an enzyme that reduces hydrogen peroxide) diminished xanthine-xanthine oxidase-induced 51Cr release in a dose-dependent manner. Superoxide dismutase (a scavenger of superoxide radical) failed to affect the amounts of 51Cr release induced by xanthine plus xanthine oxidase. Pretreatment with diethyl maleate, which depletes intracellular glutathione, potentiated oxygen radical-mediated 51Cr release dose dependently. The presence of ferrous ion or ethylenediaminetetraacetic acid-chelated iron, which promote the formation of hydroxyl radical, did not alter xanthine-xanthine oxidase-induced cellular injury. Furthermore, agents that inactivate hydroxyl radical also failed to protect the cells from oxygen metabolite-induced injury. We conclude that in vitro oxygen metabolites, extracellularly generated, have a direct toxic effect on gastric mucosal cells; hydrogen peroxide is a major mediator of oxygen metabolite-induced gastric cell injury; the oxygen-derived superoxide and hydroxyl radicals are less toxic to gastric mucosal cells than hydrogen peroxide; and intracellular glutathione, which detoxifies hydrogen peroxide, may be involved in antioxidant defense mechanisms.
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PMID:Oxygen metabolite-induced cytotoxicity to cultured rat gastric mucosal cells. 311 Dec 74

The metabolic disorder, alkaptonuria, is distinguished by elevated serum levels of 2,5-dihydroxyphenylacetic acid (homogentisic acid), pigmentation of cartilage and connective tissue and, ultimately, the development of inflammatory arthritis. Oxygen radical generation during homogentisic acid autoxidation was characterized in vitro to assess the likelihood that oxygen radicals act as molecular agents of alkaptonuric arthritis in vivo. For homogentisic acid autoxidized at physiological pH and above, yielding superoxide (O2-)2 and hydrogen peroxide (H2O2), the homogentisic acid autoxidation rate was oxygen dependent, proportional to homogentisic acid concentration, temperature dependent and pH dependent. Formation of the oxidized product, benzoquinoneacetic acid was inhibited by the reducing agents, NADH, reduced glutathione, and ascorbic acid and accelerated by SOD and manganese-pyrophosphate. Manganese stimulated autoxidation was suppressed by diethylenetriaminepentaacetic acid (DTPA). Homogentisic acid autoxidation stimulated a rapid cooxidation of ascorbic acid at pH 7.45. Hydrogen peroxide was among the products of cooxidation. The combination of homogentisic acid and Fe3+-EDTA stimulated hydroxyl radical (OH.) formation estimated by salicylate hydroxylation. Ferric iron was required for the reaction and Fe3+-EDTA was a better catalyst than either free Fe3+ or Fe3+-DTPA. SOD accelerated OH. production by homogentisic acid as did H2O2, and catalase reversed much of the stimulation by SOD. Catalase alone, and the hydroxyl radical scavengers, thiourea and sodium formate, suppressed salicylate hydroxylation. Homogentisic acid and Fe3+-EDTA also stimulated the degradation of hyaluronic acid, the chief viscous element of synovial fluid. Hyaluronic acid depolymerization was time dependent and proportional to the homogentisic acid concentration up to 100 microM. The level of degradation observed was comparable to that obtained with ascorbic acid at equivalent concentrations. The hydroxyl radical was an active intermediate in depolymerization. Thus, catalase and the hydroxyl radical scavengers, thiourea and dimethyl sulfoxide, almost completely suppressed the depolymerization reaction. The ability of homogentisic acid to generate O2-, H2O2 and OH. through autoxidation and the degradation of hyaluronic acid by homogentisic acid-mediated by OH. production suggests that oxygen radicals play a significant role in the etiology of alkaptonuric arthritis.
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PMID:Homogentisic acid autoxidation and oxygen radical generation: implications for the etiology of alkaptonuric arthritis. 312 48

Campylobacters isolated in Scotland and the north of England from bovine (497 isolates) and ovine (51 isolates) faeces were studied in order to determine which simple methods would be useful for identification of groups and species. By means of the catalase test, growth and microscopic characteristics, coccal transformation and nalidixic acid (Nal) and cephalothin sensitivity, isolates were separated into 3 groups: C. jejuni - C. coli, C. hyointestinalis - C. fetus and C. fecalis - C. sputorum subsp. bubulus. Hippurate hydrolisis was used to differentiate C. jejuni (positive) from all the other Campylobacter spp (negative). The production of hydrogen sulphide in Triple Sugar Iron was used to separate C. hyointestinalis and the C. fecalis - C. sputorum subsp. bubulus group (positive) from C. fetus (negative). The production of hydrogen sulphide in iron-bisulphite-pyruvate (FBP) medium was used to separate the C. fecalis - C. sputorum subsp. bubulus group (positive) from most C. hyointestinalis isolates (96.4% were negative). Additional characteristics useful for identification of the C. fecalis - C. sputorum subsp. bubulus group were: adherent sticky growth; inhibition of growth by FBP or ferrous sulphate and sodium metabisulphite; and inversion of Nal resistance on FBP agar. Catalase test was used to separate C. fecalis (positive) from C. sputorum subsp. bubulus (negative), although these two species should be regarded as a single species with a variable catalase test. Bovine C. hyointestinalis isolates were serologically classified as type 1 (related to the porcine C. hyointestinalis standard strain NCTC 11562) and type 2 (unrelated). Based on the above criteria, isolates in cattle were classified as: 229 C. jejuni, 66 C. coli, 112 C. hyointestinalis type 1, 53 C. hyointestinalis type 2 and 37 C. fetus. In sheep they were: 25 C. jejuni, 11 C. coli, 12 C. fecalis and 3 C. sputorum subsp. bubulus.
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PMID:Identification of campylobacters from bovine and ovine faeces. 317 20

The mechanism of cytogenetic genotoxicity (clastogenicity, induction, cell cycle delay) of 10(-3) M glutathione in V79-E cells, as described by Thust and Bach (1985), was studied in detail by using different treatment conditions. It was found that 1-cystine is the essential cofactor in the incubation system. Catalase, but not superoxide dismutase, abolished the genotoxic effect, and the iron chelator desferoxamine, as well as the hydroxyl radical scavenger mannitol, diminished the activity. It is suggested that glutathione, in combination with V79-E cells and cystine, forms a hydrogen peroxide-generating system which provokes the adverse effects. Glutathione as well as 1-cysteine and 2-mercaptopropionylglycine, which were checked for comparison, show a "paradoxic genotoxicity," i.e., at 10(-2) M the effects return almost to the level of controls. Concentration dependence and other criteria of cytogenetic genotoxicity observed with glutathione show obvious similarities to those of other oxidatively acting agents and reveal striking differences to the cytogenetic effects of "typical" genotoxins.
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PMID:The mechanism of cytogenetic genotoxicity of exogenous glutathione in V-79 cells in vitro--implication of hydrogen peroxide and general traits of oxidative chromosome damage. 323 33


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