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)

When suddenly exposed to air the growth of the obligate anaerobic bacterium of the bacteroidaceae type, strain B6, continues for a few hours before coming to a complete stop. When air is shut off soon after growth has ceased, the organism is able to reestablish anaerobic conditions due to an ability to reduce O2, and resumes normal growth after another few hours. The O2 reducing ability of the organism is due to the presence in the cells of a particle-bound NADH oxidase, a soluble NADPH oxidase and a soluble pyruvate oxidase. The two pyridine nucleotide oxidases reduce O2 to H2O2, the pyruvate oxidase reduces O2 to H2O. Catalase and peroxidase were not detected in anaerobically grown cells. Kinetic studies with cell-free extracts showed that the pyruvate oxidase had a considerably greater affinity (smaller Km) for O2 and capacity (higher Vmax) for O2 reduction than the two other oxidases. It is postulated that the pyruvate oxidase acts as a scavenger for O2, leading to the non-toxic reduction product H2O, and thus functions as a defense mechanism against oxygen toxicity when the organism is exposed to aerobic condition.
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PMID:Oxygen activation and defence against oxygen toxicity in a psychrophilic Bacteroidaceae. 271 28

The production of H2O2 by cells in cold paraformaldehyde-fixed frozen sections of inflammatory lesions was histochemically demonstrated by incubating them with diaminobenzidine (DAB) for 2 to 6 h. Catalase (150 micrograms/ml, about 1400 U/ml) inhibited the reaction, indicating that H2O2 was required to produce the chromogenic DAB product. Granulocytes (PMNs and eosinophils) were the main types of cells stained by the DAB reaction. Positive staining of macrophages was less frequent. The H2O2 was produced by metabolic enzymes that were still active after cell death and mild fixation. An atmosphere of 95 to 100% oxygen enhanced the specific DAB reaction, and an atmosphere of 100% nitrogen eliminated it. The DAB histochemical reaction to detect H2O2 requires the presence of peroxidases to produce the colored reaction product. Within our tissue sections, such peroxidases were evidently present in excess, because addition of low concentrations of H2O2 significantly increased the reaction product. Although some of the H2O2 produced by the granulocytes may have been derived from the dismutation of superoxide (O2-), the NADPH oxidase pathway for O2- formation did not seem to be involved: NADPH oxidase, a rather labile enzyme, should not be active after mild fixation, and diphenyleneiodonium (100 microM), an inhibitor of flavine-requiring NADPH oxidase, did not inhibit the reaction. Reactive nitrogen intermediates were also not involved, because NG-monomethyl-L-arginine and NG-nitro-L-arginine methyl ester, inhibitors of nitric oxide synthetase, did not appreciably inhibit the reaction. We conclude that stable, non-flavine-requiring oxidases, possibly cyclooxygenases or lipoxygenases, produced the H2O2 measured histochemically by our DAB reaction. These studies were made on tissue sections of acute dermal inflammatory lesions produced in rabbits by the topical application of 1% sulfur mustard [bis(2-chloroethyl) sulfide] in methylene chloride. Both intact PMNs and disintegrating PMNs in the base of the crust produced H2O2. Despite the production of H2O2 and the presence of peroxidase activity, no tissue damage was seen microscopically near the H2O2-producing cells, which indicates that the tissues are well protected by the antioxidants present in this self-limiting inflammatory reaction.
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PMID:Histochemical demonstration of hydrogen peroxide production by leukocytes in fixed-frozen tissue sections of inflammatory lesions. 793 Sep 39

Thymocyte apoptosis is one of the best characterized experimental models of apoptosis that can be induced by a variety of stimuli such as glucocorticoids, ionizing radiation, antibodies, and toxins. Recently, it has been suggested that oxidative stress is a common mediator of apoptosis. However, little is known about the production and possible function of reactive oxygen intermediates (ROI) in thymocytes. We used a highly sensitive flow cytometric assay with the hydrogen peroxide-sensitive dye, 2',7'-dichlorofluorescin diacetate (DCFH-DA), to measure intracellular ROI production in rat thymocytes, to study its primary sources, and to compare ROI levels in normal and apoptotic thymocytes. Apoptosis was induced by incubating the cells in the presence or absence of dexamethasone (Dex) at 37 degrees C in vitro. Normal thymocytes spontaneously produced significant amounts of ROI. Catalase or superoxide dismutase did not affect this intracellular fluorescence, presumably due to their failure to penetrate into the cells. However, N-acetyl-L-cysteine significantly attenuated the fluorescence in a dose-dependent manner. Significant inhibition of the intracellular fluorescence was also observed by addition of N-nitro-L-arginine methyl ester (L-NAME), that could not be reversed by L-arginine. The addition of N-nitro-D-arginine methyl ester (D-NAME) also caused considerable inhibition. This indicates that the inhibition by L-NAME or D-NAME is due to a direct scavenging effect, and nitric oxide production is not likely to be involved. In contrast to neutrophils and macrophages whose superoxide anions are released from membrane-bound NADPH oxidase, the production of ROI in thymocytes is likely to originate mainly from mitochondria, as indicated by the inhibitory effect of the addition of rotenone or antimycin A. The addition of lymphocyte simulators phytohemagglutinin (PHA), concanavalin A (Con A), or phorbol 12-myristate 13-acetate (PMA) enhanced intracellular fluorescence of thymocytes. This increase was abrogated by addition of rotenone or antimycin A. The ROI production was decreased with time after incubation of the thymocytes for 1, 3, and 6 h in vitro. The appearance of apoptosis of thymocytes in vitro, as indicated by DNA content of cells by flow cytometry and DNA ladder formation in agarose gel electrophoresis, was delayed, as compared to the time course of the decreased ROI production. The addition of Dex to the culture medium accelerated both of these processes. The results suggest that a decreased spontaneous production of ROI in thymocytes precedes the spontaneous in vitro apoptosis and Dex exaggerates these changes.
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PMID:Decreased production of reactive oxygen intermediates is an early event during in vitro apoptosis of rat thymocytes. 890 94

Oocysts of Cryptosporidium parvum showed relatively low levels of SOD activity. The SOD which had a pI of 4.8 and an approximate molecular weight of 35 kDa appeared to be iron dependent. Catalase, glutathione transferase, glutathione reductase and glutathione peroxidase activity could not be detected, nor could trypanothione reductase. No NADH or NADPH oxidase activity could be detected, nor could peroxidase activity be demonstrated using o-dianisidine, guaiacol, NADPH or NADH as co-substrates. However, an NADPH-dependent H2O2 scavenging system was detected in the insoluble fraction.
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PMID:Anti-oxidant enzymes in Cryptosporidium parvum oocysts. 901 Oct 70

The active oxygen species hydrogen peroxide (H2O2) was detected cytochemically by its reaction with cerium chloride to produce electron-dense deposits of cerium perhydroxides. In uninoculated lettuce leaves, H2O2 was typically present within the secondary thickened walls of xylem vessels. Inoculation with wild-type cells of Pseudomonas syringae pv phaseolicola caused a rapid hypersensitive reaction (HR) during which highly localized accumulation of H2O2 was found in plant cell walls adjacent to attached bacteria. Quantitative analysis indicated a prolonged burst of H2O2 occurring between 5 to 8 hr after inoculation in cells undergoing the HR during this example of non-host resistance. Cell wall alterations and papilla deposition, which occurred in response to both the wild-type strain and a nonpathogenic hrpD mutant, were not associated with intense staining for H2O2, unless the responding cell was undergoing the HR. Catalase treatment to decompose H2O2 almost entirely eliminated staining, but 3-amino-1,2,4-triazole (catalase inhibitor) did not affect the pattern of distribution of H2O2 detected. H2O2 production was reduced more by the inhibition of plant peroxidases (with potassium cyanide and sodium azide) than by inhibition of neutrophil-like NADPH oxidase (with diphenylene iodonium chloride). Results suggest that CeCl3 reacts with excess H2O2 that is not rapidly metabolized during cross-linking reactions occurring in cell walls; such an excess of H2O2 in the early stages of the plant-bacterium interaction was only produced during the HR. The highly localized accumulation of H2O2 is consistent with its direct role as an antimicrobial agent and as the cause of localized membrane damage at sites of bacterial attachment.
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PMID:Localization of hydrogen peroxide accumulation during the hypersensitive reaction of lettuce cells to Pseudomonas syringae pv phaseolicola. 906 52

The ability of Campylobacter jejuni to penetrate normally nonphagocytic host cells is believed to be a key virulence determinant. Recently, kinetics of C. jejuni intracellular survival have been described and indicate that the bacterium can persist and multiply within epithelial cells and macrophages in vitro. Studies conducted by Pesci et al. indicate that superoxide dismutase contributes to intraepithelial cell survival, as isogenic sod mutants are 12-fold more sensitive to intracellular killing than wild-type strains. These findings suggest that bacterial factors that combat reactive oxygen species enable the organism to persist inside host cells. Experiments were conducted to determine the contribution of catalase to C. jejuni intracellular survival. Zymographic analysis indicated that C. jejuni expresses a single catalase enzyme. The gene encoding catalase (katA) was cloned via functional complementation, and an isogenic katA mutant strain was constructed. Kinetic studies indicate that catalase provides resistance to hydrogen peroxide in vitro but does not play a role in intraepithelial cell survival. Catalase does however contribute to intramacrophage survival. Kinetic studies of C. jejuni growth in murine and porcine peritoneal macrophages demonstrated extensive killing of both wild-type and katA mutant strains shortly following internalization. Long-term cultures (72 h postinfection) of infected phagocytes permitted recovery of viable wild-type C. jejuni; in contrast, no viable katA mutant bacteria were recovered. Accordingly, inhibition of macrophage nitric oxide synthase or NADPH oxidase permitted recovery of katA mutant C. jejuni. These observations indicate that catalase is essential for C. jejuni intramacrophage persistence and growth and suggest a novel mechanism of intracellular survival.
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PMID:Role of catalase in Campylobacter jejuni intracellular survival. 1103 43

Oxidative damage plays a key role in septic shock induced by lipopolysaccharide (LPS) which is known to enhance the formation of reactive oxygen species (ROS). In this study, biochemical parameters indicative of oxidative stress were tested in the rat heart following LPS challenge, with and without pretreatment with the antioxidants NAO (natural antioxidant) and apocynin. NAO is a natural antioxidant isolated and purified from spinach and its main components are flavonoids and coumaric acid derivatives. Treatment with LPS alone significantly (P<0.05) increased the malondialdehyde (MDA) level in heart, both in cytosolic and mitochondrial fractions by 1.5- and 2.4-fold, respectively, and in plasma (2.66 fold). In the heart homogenate, the level of hydroperoxides also increased significantly (P<0.05). In addition, LPS treatment significantly (P<0.05) increased NADPH oxidase activity in the heart microsomal fraction by approximately 10-fold compared to control. Pretreatment for 7 days with either apocynin or NAO prior to the LPS challenge significantly (P<0.05) improved rat survival, decreased MDA levels in both fractions and decreased microsomal NADPH-oxidase activity, compared to LPS alone. Catalase (CAT) activity slightly increased at 24 h post-LPS injection in LPS group and returned to the control level in the apocynin treated group. No meaningful changes were indicated for glutathione peroxidase activity among all the treatment groups. The activities of cytosolic and mitochondrial superoxide dismutase (SOD) enzymes significantly (P<0.05) increased approximately 20% in the LPS-treated group, compared to control. Apocynin significantly (P<0.05) decreased SOD level in the mitochondrial fraction with no effect on the cytosolic fraction; whereas, NAO had no important effect on SOD level in both fractions. The beneficial pretreatment effects of the antioxidants against oxidative stress in the rat heart presented in this study may suggest a potential chemopreventive effect of this compound in sepsis prevention.
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PMID:The effect of natural antioxidants, NAO and apocynin, on oxidative stress in the rat heart following LPS challenge. 1151

We studied whether reactive oxygen species (ROS) generated by normal colonic mucosa affect 5-hydroxytryptophan (5-HTP)-evoked 5-HT formation (measured as the sum of 5-HT plus 5-hydroxyindole acetic acid (5-HIAA) accumulation) of guinea pig's isolated colonic mucosa. Catalase (3000-6000 U/ml), a hydrogen peroxide (H2O2) scavenger or diphenylene iodonium (DPI, 10-100 microM), an NADPH oxidase inhibitor, concentration-dependently caused an increase of the sum of 5-HT plus 5-HIAA accumulation in the presence of 5-HTP (10 microM), but these drugs did not significantly affect the 5-HT-metabolite in the colonic mucosa measured as the ratio of 5-HIAA/5-HT. Exogenously applied H2O2 (10-100 microM) concentration-dependently inhibited the sum of 5-HT plus 5-HIAA accumulation. In contrast, neither superoxide dismutase (SOD, 100-300 U/ml), superoxide anion scavenger, nor dimetyl sulfoxide (1-5%, DMSO), a hydroxyl radical scavenger affected the sum of 5-HT plus 5-HIAA accumulation. Moreover, mucosa ROS generation was estimated using the chemiluminescence technique. SOD (100-300 U/ml), catalase (3000-6000 U/ml) or DPI (10-100 microM), concentration-dependently reduced luminol-enhanced chemiluminescence signal from the colonic mucosa, while allopurinol (10-100 microM), a xanthine oxidase inhibitor, did not affect the chemiluminescence signal. These results suggest that ROS is formed through an NADPH oxidase system in the guinea pig colonic mucosa, where it exerts a modulatory effect on mucosal 5-HT formation upon addition of 5-HTP. Thus, ROS formation from normal colonic mucosa could be considered to contribute to the control of 5-HT production in mucosa enterochromaffin cells.
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PMID:Modification of 5-hydroxytryptophan-evoked 5-hydroxytryptamine formation of guinea pig colonic mucosa by reactive oxygen species. 1185 70

The purpose of this study was to assess and compare the toxicity of beta-amyloid (Abeta) on primary cortical and mesencephalic neurons cultured with and without microglia in order to determine the mechanism underlying microglia-mediated Abeta-induced neurotoxicity. Incubation of cortical or mesencephalic neuron-enriched and mixed neuron-glia cultures with Abeta(1-42) over the concentration range 0.1-6.0 microm caused concentration-dependent neurotoxicity. High concentrations of Abeta (6.0 microm for cortex and 1.5-2.0 microm for mesencephalon) directly injured neurons in neuron-enriched cultures. In contrast, lower concentrations of Abeta (1.0-3.0 microm for cortex and 0.25-1.0 microm for mesencephalon) caused significant neurotoxicity in mixed neuron-glia cultures, but not in neuron- enriched cultures. Several lines of evidence indicated that microglia mediated the potentiated neurotoxicity of Abeta, including the observations that low concentrations of Abeta activated microglia morphologically in neuron-glia cultures and that addition of microglia to cortical neuron-glia cultures enhanced Abeta-induced neurotoxicity. To search for the mechanism underlying the microglia-mediated effects, several proinflammatory factors were examined in neuron-glia cultures. Low doses of Abeta significantly increased the production of superoxide anions, but not of tumor necrosis factor-alpha, interleukin-1beta or nitric oxide. Catalase and superoxide dismutase significantly protected neurons from Abeta toxicity in the presence of microglia. Inhibition of NADPH oxidase activity by diphenyleneiodonium also prevented Abeta-induced neurotoxicity in neuron-glia mixed cultures. The role of NADPH oxidase-generated superoxide in mediating Abeta-induced neurotoxicity was further substantiated by a study which showed that Abeta caused less of a decrease in dopamine uptake in mesencephalic neuron-glia cultures from NADPH oxidase-deficient mutant mice than in that from wild-type controls. This study demonstrates that one of the mechanisms by which microglia can enhance the neurotoxicity of Abeta is via the production of reactive oxygen species.
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PMID:Microglia enhance beta-amyloid peptide-induced toxicity in cortical and mesencephalic neurons by producing reactive oxygen species. 1242 70

Previous studies have shown that a constitutively active isoform of Ras is able to produce superoxide radical (O2(-)). The present study investigate the mechanisms by which O2(-) radical mediates signals from Ras protein to the nucleus, leading to cellular responses such as apoptosis in Cr(VI)-stimulated cells. Two human prostate tumor cell lines, Ras(+), which overexpresses Ras, and Ras(-), which has a normal Ras level, were utilized. Compared to Ras(-) cells, Ras(+) cells exhibited higher susceptibility to apoptosis induced by Cr(VI). Catalase, sodium formate, and deferoxamine inhibited Cr(VI)-induced apoptosis. Similar differences were observed in both cellular DNA damage and the activation of p53 protein. The differences in Cr(VI)-induced cell responses in Ras(+) and Ras(-) cells were due to differences in the generation of free radicals between these two cells. ESR spin trapping measurements showed that Ras(+) cells generated more hydroxyl radical ((.)OH), O2(-) radical, and Cr(V) than Ras(-) cells following Cr(VI) stimulation. The generation of the reactive oxygen species (ROS) can be abolished by the addition of superoxide dismutase (SOD) or if the experiment were carried out in an argon atmosphere. Catalase inhibited spin adduct signals but was much less potent than SOD. The mechanism of ROS generation in Cr(VI)-stimulated Ras(+) cells involves the reduction of molecular oxygen to O2(-) radical by a flavoenzyme-containing NADPH oxidase complex as shown by oxygen consumption and diphenylene iodonium (DPI) inhibition. Results shown above support the following conclusions: (a) Ras protein mediates O2(-) radical generation through reduction of molecular oxygen by NADPH oxidase in Cr(VI)-stimulated cells. (b) The O2(-) radical and Cr(VI) produce other reactive species, including H2O2, OH radical, and Cr(V) through O2(-) dismutation and Haber-Weiss type of reactions. (c) Among these reactive species, (.)OH radical is responsible for the further transduction of signals from Ras to the nucleus, leading to various cell responses.
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PMID:Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction. 1497 53


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