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At least 1,603 records · Page 89Linked to original sources
PubMed2003

Enhancement of catalase activity by repetitive low-grade H2O2 exposures protects fibroblasts from subsequent stress-induced apoptosis.

Exposure of Chinese hamster V79 fibroblasts to mild and repetitive H2O2 doses in culture for 15 weeks produced no change in lipid peroxidation status, GSH/GSSG ratio and glutathione peroxidase activity of these cells (VST cells). In contrast, in VST cells catalase levels underwent a prominent increase which could be significantly inhibited and brought down to control levels after treatment with the catalase inhibitor 3-aminotriazole (3-AT). When control (VC) cells were exposed to UV radiation (UVC 5 J/m2) or H2O2 (7.5mM, 15 min), intracellular reactive oxygen species (ROS) levels rose prominently with significant activation of caspase-3. Marked nuclear fragmentation and lower cell viability were also noted in these cells. In contrast, VST cells demonstrated a significantly lower ROS level, an absence of nuclear fragmentation and an unchanged caspase-3 activity after exposure to UVC or H2O2. Cell viability was also significantly better preserved in VST cells than VC cells after UV or H2O2 exposures. Following 3-AT treatment of VST cells, UVC radiation or H2O2 brought about significantly higher elevations in intracellular ROS, increases in caspase-3 activity, significantly lowered cell viability and marked nuclear fragmentation, indicating the involvement of high catalase levels in the cytoprotective effects of repetitive stress. Therefore, upregulation of the antioxidant defense after repetitive oxidative stress imparted a superior ability to cope with subsequent acute stress and escape apoptotic death and loss of viability.

Amitrole↗
PubMed2003

Stress protein response and catalase activity in freshwater planarian Dugesia (Girardia) schubarti exposed to copper.

The hsp60 expression pattern and catalase activity in the freshwater planarian Dugesia schubarti exposed to copper under laboratory conditions were investigated. In the hsp60 induction experiments, planarians were exposed to a range of copper concentrations (0-960 microgCu/L) for 4 or 24h, to concentrations of 50 or 100 microgCu/L for 2, 4, 8, and 24h at 19 degrees C, and to heat shock at 27 degrees C for 24h. The concentrations of hsp60 in whole-body homogenates were determined immunochemically by Western blotting. Stress protein induction was detected only after 24h treatment at 27 degrees C. The tissue concentration of hsp60 remained unaltered in Cu-exposed planarians under the experimental conditions used. Catalase activity was significantly induced at concentrations of 40, 80, and 160 microgCu/L after 24h exposure. Our results suggest that catalase levels in planarians could represent biomarkers of interest for the estimation of copper effects in freshwater ecosystems.

Animals↗
PubMed2000

Differential developmental expression and cell type specificity of Dictyostelium catalases and their response to oxidative stress and UV-light.

Cells of Dictyostelium discoideum are highly resistant to DNA damaging agents such as UV-light, gamma-radiation and chemicals. The genes encoding nucleotide excision repair (NER) and base excision repair (BER) enzymes are rapidly upregulated in response to UV-irradiation and DNA-damaging chemicals, suggesting that this is at least partially responsible for the resistance of this organism to these agents. Although Dictyostelium is also unusually resistant to high concentrations of H(2)O(2), little is known about the response of this organism to oxidative stress. To determine if transcriptional upregulation is a common mechanism for responding to DNA-damaging agents, we have studied the Dictyostelium catalase and Cu/Zn superoxide dismutase antioxidant enzymes. We show that there are two catalase genes and that each is differentially regulated both temporally and spatially during multicellular development. The catA gene is expressed throughout growth and development and its corresponding enzyme is maintained at a steady level. In contrast, the catB gene encodes a larger protein and is only expressed during the final stages of morphogenesis. Cell type fractionation showed that the CatB enzyme is exclusively localized to the prespore cells and the CatA enzyme is found exclusively in the prestalk cells. Each enzyme has a different subcellular localization. The unique developmental timing and cell type distribution suggest that the role for catB in cell differentiation is to protect the dormant spores from oxidative damage. We found that exposure to H(2)O(2) does not result in the induction of the catalase, superoxide dismutase, NER or BER mRNAs. A mutant with greatly reduced levels of catA mRNA and enzyme has greatly increased sensitivity to H(2)O(2) but normal sensitivity to UV. These results indicate that the natural resistance to oxidative stress is not due to an ability to rapidly raise the level of antioxidant or DNA repair enzymes and that the response to UV-light is independent from the response to reactive oxygen compounds.

Amino Acid Sequence↗
PubMed2001

Isolation and characterisation of a cassava catalase expressed during post-harvest physiological deterioration.

Storage roots of cassava undergo a rapid, endogenous, post-harvest deterioration response that is thought to involve oxidative processes. A cassava catalase (MecCAT1) was isolated from a root cDNA library. The transcript is expressed predominantly in roots with little expression in leaves. Catalase enzyme activity and MecCAT1 transcript expression during the post-harvest period were compared in highly susceptible and less susceptible cultivars and suggest that high levels of catalase activity may play a role in delaying the deterioration response.

Amino Acid Sequence↗
PubMed1996

Reaction of E. coli catalase HPII with cyanide as ligand and as inhibitor.

Cyanide forms an inhibitory complex with the haem d-containing E. coli catalase HPII, spectrally similar to the cyanide complex of beef liver enzyme but with absorption bands shifted 90 nm towards the red end of the spectrum. Both the Kd and Ki values are approximately 7 microM in the wild-type enzyme. The cyanide reaction is slow, with a bimolecular 'on' constant approx. 2000 x smaller than that of eukaryotic enzyme, and an 'off' constant diminished by a similar amount. Catalases with a mutated distal histidine (H128) fail to bind cyanide at cyanide concentrations below 50 mM. Catalases with a mutated distal asparagine (N201) show only small changes in cyanide affinity from the wild type. The major fraction of HPII N201A has a Kd approximately 40 microM, and a minor fraction has a lower cyanide affinity; the major fraction of HPII N201Q has a Kd approximately 15 microM. The Kd and Ki for HPII N201D is approximately 8 microM, essentially identical with that of the wild type but N201D appears to bind cyanide somewhat more rapidly than does wild-type enzyme. The HPII mutant N201H can be obtained in both haem d and protohaem forms; it exhibits two types of cyanide binding behaviour. In its protohaem form it binds cyanide poorly (Kd > or = 0.25 mM). After peroxide treatment converts t into haem d or a closely related species it binds cyanide with a much higher affinity (Kd approximately 15 microM). Cyanide binding to HPII requires a distal histidine to provide hydrogen-bonding stability, but not a distal asparagine. Rates of cyanide binding and release are controlled by haem group accessibility through the channel leading to the outside. In HPII N201H channel opening may depend upon oxidation of the haem from the starting protohaem to the final haem d form.

Animals↗
PubMed1998

E. coli HPII catalase interaction with high spin ligands: formate and fluoride as active site probes.

E. coli catalase (HPII) wild type and mutant enzymes (heme dcis-containing) were examined (i) to study the role of a distal haem cavity residue, asparagine-201, in high spin ligand binding and (ii) to compare the differences in this binding between heme d and protoheme enzymes such as that from beef liver (BLC). High spin fluoride complexes were formed by all three HPII catalases examined, wild type (201 asn) and 201gln and 201asp mutants, but with a lower fluoride affinity than that of BLC. The binding of fluoride was pH-dependent, indicating that a proton is bound as well as a fluoride anion. HPII 201glu and 201 asp mutants showed lower affinities for fluoride than did wild type, unlike their reactions with cyanide which are essentially independent of the nature of residue 201. The equilibria and rates of fluoride and formate binding to BLC were reexamined. The rates of reaction with formate were similar to those reported previously. Dissociation rates for fluoride-catalase are higher than for formate suggesting that the latter may be bound differently. High spin complexes between formate and all three HPII forms showed a substantially higher affinity than that of BLC for HPII wild type and progressively lower affinities for the two mutants. As with fluoride the reactions were pH-dependent, indicating that a proton is bound together with the formate anion (or that undissociated formic acid is the ligand). The known structures of the heme groups and heme pockets involved are discussed. Formate may be bound by secondary H-bounds within the heme pocket in both heme dcis and protoheme enzymes. The nature of the heme pocket and the heme access channel may be more important than the chemical nature of the prosthetic group in controlling both high spin ligand interactions and reactions with the substrate hydrogen peroxide.

Bacterial Proteins↗
PubMed1999

Lysyl oxidase coupled with catalase in egg shell membrane.

The activity of lysyl oxidase was found in egg shell membrane (ESM) of hens. The activity was determined by measuring the enzymatic conversion of n-butylamine and Nalpha-acetyl-L-lysine to n-butyraldehyde and Nalpha-acetyl-L-allysine, respectively. ESM lysyl oxidase was significantly inhibited by beta-aminopropionitrile, chelating agents, and deoxygenation, consistent with the known properties of lysyl oxidase. Nevertheless, ESM lysyl oxidase was insoluble in urea solution, suggesting that it complexes with ESM. These findings support previous reports indicating the presence of lysine-derived cross-links in ESM and the necessity of lysyl oxidase located in the isthmus of the hen oviduct for the biosynthesis of ESM. Lysyl oxidase secreted around the egg white from the isthmus may initiate the cross-linking reaction of ESM protein, and remain as the constituent of ESM. Moreover, the H(2)O(2) released by lysyl oxidase in ESM was completely decomposed by coexisting catalase activity. ESM lysyl oxidase activity was greatly elevated in the presence of H(2)O(2), probably due to the O(2) produced by catalase. These findings indicate that lysyl oxidase is coupled with catalase in ESM. This coupling enzyme system was considered to be involved in the biosynthesis of ESM and to protect the embryo against H(2)O(2).

Animals↗
PubMed2002

Immune responses in mice to intranasal and intracutaneous administration of a DNA vaccine encoding Helicobacter pylori-catalase.

We previously reported that the intracutaneous injection of DNA vaccines encoding Helicobacter pylori heat shock proteins elicited specific immune responses, and led to reduced infection in mice. In this study, we constructed DNA vaccine encoding H. pylori-catalase (pcDNA3.1-kat) and investigated the immune responses to intranasal and intracutaneous administration of pcDNA3.1-kat. C57/BL6 mice were immunized intracutaneously with 10 microg of pcDNA3.1-kat or intranasally with 50 microg of pcDNA3.1-kat. Catalase-specific IgG antibody was detected in the sera of intranasal and intracutaneous immunized mice. Both intranasal and intracutaneous immunized mice were significantly protected from colonization by H. pylori and had significantly reduced degrees of gastritis. These results demonstrate that DNA vaccine encoding H. pylori-catalase can induce an immune response against H. pylori, and that intranasal immunization works as well as intracutaneous immunization.

Administration, Intranasal↗
PubMed2001

Inactivation of catalase and superoxide dismutase by singlet oxygen derived from photoactivated dye.

Both superoxide dismutase (SOD) and catalase are key enzymes in the antioxidant system of the cells that work to maintain low steady-state concentrations of the reactive oxygen species. When exposed to a singlet oxygen-producing system composed of dye, such as methylene blue or rose bengal, and visible light both SOD and catalase were susceptible to oxidative modification and damage as indicated by the loss of activity, fragmentation and aggregation of peptide as well as by the formation of carbonyl groups. Histidine, a powerful quenching agent for singlet oxygen, and the polyamines, such as spermine and spermidine, were effective at protecting the activity loss mediated by illuminated dye, whereas spin traps were only mildly effective. The structural alterations of modified enzymes were indicated by the increase in susceptibility to proteases, the change in absorption spectra and in fluorescence spectra. The singlet oxygen-mediated damage to SOD and catalase may result in the perturbation of cellular antioxidant defense mechanisms and subsequently lead to a pro-oxidant condition.

Animals↗
PubMed1997

Oxidative stress to DNA, protein, and antioxidant enzymes (superoxide dismutase and catalase) in rats treated with benzo(a)pyrene.

Oxidative DNA damage (as 8-hydroxydeoxyguanosine; 8-OHdG), carbonyl content of proteins, and activities of superoxide dismutase (SOD) and catalase were investigated in female Sprague-Dawley rats orally treated with benzo(a)pyrene (B(a)P) (75 mg/rat). HPLC-ECD system showed that B(a)P increased the level of 8-OHdG in tissues (liver, kidney, and lung), but a statistical significance was observed only in the liver (3.5-fold increase) and kidney (two-fold increase). In the liver, the peak level (21 +/- 5 8-OHdG residues/10(5) dG) was obtained 12 h after treatment and returned close to control level (9 +/- 2 8-OHdG residues/10(5) dG) at 24 h, but 8-OHdG was persistent in the kidney. Carbonyl contents measured as an index of protein oxidation were slightly increased (23-35%) in the cytosolic fraction of tissues, but a significant increase (2.19 nmol/mg protein, 35% increase) was observed only in the liver 6 h after treatment, similar to 8-OHdG. However, the rate of increase was relatively low compared to that of 8-OHdG. In contrast to DNA and protein damages, the activities of SOD and catalase in the tissues were decreased after treatment (P < 0.01) and gradually increased to control levels. SOD and catalase activities in organs of rats were inversely correlated with oxidative damages to DNA and protein. The data suggest that B(a)P oxidatively altered DNA, protein, and antioxidant enzymes in rats and this might be associated with B(a)P carcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

An association study of a functional catalase gene polymorphism, -262C-->T, and patients with Alzheimer's disease.

According to the oxidative stress hypothesis which has been proposed as one of a number of possible mechanisms underlying pathogenesis of Alzheimer's disease (AD), accumulation of hydrogen peroxide in the brain of affected individuals, due to overproduction and/or insufficient detoxification, can trigger a cascade of neurotoxic events, thus contributing to the neuronal damage characteristic of the disease. The upregulation of enzymes that are able to neutralize hydrogen peroxide (catalase, peroxidases) would then be conceivably able to offer at least some protection from the damaging effects of this agent. In this study we examined the distribution of a functional polymorphism in the gene for catalase, -262C-->T, in an independent population of 137 AD patients and 130 control individuals. The presence of the polymorphism, which results in the elimination of a SmaI restriction site, was tested with a PCR amplification/SmaI digestion-based assay. No significant difference has emerged from the comparison of either genotype or allele frequencies (P>0.5). We conclude that the catalase gene -262C-->T polymorphism does not confer a protective effect with respect to AD.

Aged↗
PubMed2002

Changes in superoxide dismutase and catalase activities of rat brain regions during early global transient ischemia/reperfusion.

It has been widely recognized that the hippocampus and striatum are clearly more susceptible to oxidative stress than the remaining brain regions. However, the mechanism involved is not known. The activities of the antioxidant enzymes CuZn-superoxide dismutase (SOD), Mn-SOD and catalase were measured in the hippocampus and striatum and the results were compared to cortex and cerebellum (less susceptible to oxidative stress) after 3 h of a global transient ischemia/reperfusion. CuZn-SOD activities were reduced in all brain regions, but mainly in the hippocampus and striatum. Mn-SOD activity was lowered in the striatum, whereas catalase activity was reduced in the hippocampus and striatum. Our findings indicate that in the earlier phase of ischemia/reperfusion the decay in activities of catalase and SOD may be related with the high susceptibility of the hippocampus and striatum to oxidative damage.

Animals↗
PubMed1998

Diperoxovanadate participates in peroxidation reactions of H2O2 in presence of abundant catalase.

Vanadate forms a stable complex with H2O2 at pH 7.0 in competition with catalase and the product, diperoxovanadate, resists scavenger action of catalase. Diperoxovanadate can act as a substrate in a H2O2-user reaction, horseradish peroxidase and can take the place of H2O2 far more effectively in oxidatively inactivating glyceraldehyde-3-phosphate dehydrogenase. By forming peroxo-complexes vanadate can provide a way of preserving cellular H2O2 in presence of abundant catalase and make it available for its functions.

Animals↗
PubMed1997

Possible involvement of catalase in the protective effect of interleukin-6 against 6-hydroxydopamine toxicity in PC12 cells.

We examined the effects of various neurotrophic factors and cytokines on 6-hydroxydopamine (6-OHDA)-induced toxicity in PC12 cells. Exposure of PC12 cells to 6-OHDA resulted in a concentration- and time-dependent cell death, as evidenced by the release of lactate dehydrogenase into the culture medium. Addition of catalase, but not superoxide dismutase, to the culture medium protected PC12 cells from the 6-OHDA-induced toxicity. Interleukin (IL)-6 provided a dose-dependent protection against the 6-OHDA toxicity, as did nerve growth factor (NGF). In addition, basic fibroblast growth factor and dibutyryl cyclic AMP partially protected PC12 cells from 6-OHDA toxicity. Neither IL-1alpha, IL-2, IL-4, transforming growth factor-beta, nor leukemia inhibitory factor had any effect. The protective effect of IL-6 was attenuated by 3-amino-1,2,4-triazole, an inhibitor of catalase. These results suggest that IL-6 may protect PC12 cells against the 6-OHDA toxicity by activating free radical detoxifying mechanisms, such as catalase activity.

Animals↗
PubMed2003

Role of catalase in ethanol-induced conditioned taste aversion: a study with 3-amino-1,2,4-triazole.

Recent studies involved acetaldehyde, the first ethanol metabolite, in both the rewarding and aversive effects of ethanol consumption. Brain acetaldehyde is believed to originate mainly from local brain metabolism of ethanol by the enzyme catalase. Therefore, the inhibition of catalase by 3-amino-1,2,4-triazole (aminotriazole) may help to clarify the involvement of acetaldehyde in ethanol's hedonic effects. In the present study, multiple doses of both ethanol and aminotriazole were used to investigate the effects of catalase inhibition on ethanol-induced conditioned taste aversion (CTA). A separate microdialysis experiment investigated the effects of aminotriazole pretreatment on the time course of brain ethanol concentrations. Ethanol induced a dose-dependent CTA with a maximal effect after conditioning with 2.0 g/kg ethanol. Aminotriazole pretreatments dose-dependently potentiated the CTA induced by 1.0 g/kg ethanol. However, aminotriazole pretreatments did not alter the CTA induced by higher ethanol doses (1.5 and 2.0 g/kg) probably because a maximal aversion for saccharin was already obtained without aminotriazole. The results of the microdialysis experiment confirmed that the effects of aminotriazole cannot be attributed to local alterations of brain ethanol levels. The present study argues against a role for brain acetaldehyde in ethanol's aversive effects but in favor of its involvement in ethanol rewarding properties.

Acetaldehyde↗
PubMed2002

Relative contributions of heart mitochondria glutathione peroxidase and catalase to H(2)O(2) detoxification in in vivo conditions.

This study was aimed at assessing the relative contributions to H(2)O(2) detoxification by glutathione peroxidase and catalase in the mitochondrial matrix of heart. For this purpose, mitoplasts from rat heart were used in order to minimize contamination with microperoxisomes, and the kinetic rate constants of both enzymatic activities were determined along with a simulation profile. Results show that the contribution of catalase to H(2)O(2) removal in heart mitochondria is not significant, even under strong oxidative conditions, such as those achieved in ischemia-reperfusion and involving extensive glutathione depletion and high H(2)O(2) concentrations. Conversely, maintenance of the steady state levels of H(2)O(2) in the heart mitochondrial matrix seems to be the domain of glutathione peroxidase. It is suggested that the physiological role of the low amounts of catalase found in heart mitochondria is related to its peroxidatic rather than catalatic activity.

Animals↗
PubMed1997

TGF-beta1 triggers oxidative modifications and enhances apoptosis in HIT cells through accumulation of reactive oxygen species by suppression of catalase and glutathione peroxidase.

Transforming growth factor-beta1 (TGF-beta1) is a multifunctional polypeptide that is related to the progression of chronic pancreatitis. However, the mechanism of beta-cell damage by TGF-beta1 is unknown. Treatment with TGF-beta1 enhanced internucleosomal DNA cleavage caused by exogenous hydrogen peroxide in a hamster pancreatic beta-cell line (HIT). TGF-beta1 also induced protein oxidation, assessed by measuring carbonyl groups in proteins, and was involved in reactions that lead to lipid peroxidation. This eventually destructs membrane lipids and forms malondialdehyde. We have investigated its effects on two major antioxidative enzymes, catalase and glutathione peroxidase (GPx). TGF-beta1 suppressed mRNA expression as well as reduced the activities of catalase and GPx. The decrease in the catalase and GPx activities in TGF-beta1-treated cells resulted in an increase in intracellular peroxides as judged by flow cytometric analysis using a peroxide-sensitive dye, 2',7'-dichlorofluorescin diacetate. These data suggest that the augmented production of reactive oxygen species by TGF-beta1 through suppression of antioxidative enzymes may cause cellular damage and consequent apoptosis and induce pancreatitis or diabetes.

Adenoma, Islet Cell↗
PubMed1997

Regulation of catalases in Arabidopsis.

The catalase multi-gene family in Arabidopsis includes three genes encoding individual subunits which associate to form at least six isozymes that are readily resolved by non-denaturing gel electrophoresis. CAT1 and CAT3 map to chromosome 1, and CAT2 maps to chromosome 4. The nucleotide and deduced amino acids sequences of the three coding regions are highly related to each other and to other catalases. Both the individual isozymes and the individual subunit mRNAs show distinct patterns of spatial (organ-specific) expression. Six isozymes are detected in flowers and leaves and two are seen in roots. All three mRNAs are highly expressed in inflorescences, and CAT2 and CAT3 are highly expressed in leaves. All three mRNAs are detectable in freshly imbibed seeds, although the pattern of mRNA relative abundance varies among the three genes during early germination. CAT1 and CAT2 mRNA abundance is induced by light. In contrast, CAT3 is negatively light-responsive. CAT2 and CAT3 mRNA abundance is controlled by the circadian clock. Interestingly, the peak in CAT3 mRNA abundance occurs in the subjective evening, which is out of phase with expression of the Arabidopsis CAT2 catalase gene that shows clock-regulated expression gated to the subjective early morning. CAT1 mRNA abundance is not clock-regulated.

Arabidopsis↗