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)

We examined the combined effects of gamma-radiation (24 degrees C) on spores of Clostridium botulinum-type Eklund strain suspended in different gas-saturated Na-phosphate buffer in absence or presence of protectors or sensitizers. Response surface methodology (RSM) was also used to ascertain the effects of radiation on the recovery of spores using a medium containing various levels of NaCl or Na-thioglycollate. The former (< 0.5%) decreased viable spore counts, but the latter (0.15%) did not. Irradiation inactivation of Eklund spores was most effective in air-saturated buffers compared to N2O and N2 gas. The Na2-EDTA (0.01 M) was the most efficient radioprotector of spores due to its reactivity toward hydroxy radicals, followed by t-butanol (0.1 M) in NO2 or N(2)-saturated buffers, respectively. Catalase (10.0 mg ml(-1)) and DL-cysteine (0.1 mM) sensitized the spores during irradiated N2O or N(2)-saturated buffers, and NaCl (0.01 M) only sensitized spores in N2 environment. Spores frozen at -75 degrees C for 30 days and thawed prior to use were more sensitive to radiation damage compared to freshly prepared spores. Glycerol (15%), in Na-phosphate buffer (pH 7.0, 0.06 M), protected Eklund spores and increased the number of spores from 10(6) to 10(11) colony forming unit (CFU) ml(-1), and enhanced their radiosensitivities. Seven strains of C. botulinum type E were screened for plasmids and strain BL764 had two plasmids (15.8 and 46.8 mDa), BL4028 also had two (4.4 and 13.2 mDa), BL4850 contained only one (4.9 mDa), whereas EQA, BL211, Eklund, and Beluga had none. Gamma-Radiation (10 kGy, absorbed dose) cured the 15.8-mDa plasmid in strain BL764, but its absence yielded no changes in toxigenicity.
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PMID:Combined effects of ionizing-irradiation and different environments on Clostridium botulinum type E spores. 1462 91

Problems caused by the presence of adventitious metals in buffers and reagents are well recognized in studies of metal-catalyzed oxidation reactions. In most cases, metal contamination leads to an increase in rate, and chelating agents are inhibitory. In the present study, however, the rate of copper-catalyzed oxidation of cysteine was found to be increased by buffer purification with Chelex resin or by addition of micromolar concentrations of the specific iron chelator desferrioxamine (DFO). These effects are attributable to inhibition of copper-catalyzed oxidation by adventitious iron. In purified buffer at pH 7.25, containing 0.4 microM copper, cysteine was oxidized at a rate of 32 microM/min. Addition of iron salts to this buffer caused a dose-related decrease in this rate, up to a maximum of 85%. A 50% decrease in rate was recorded at an iron concentration of only 11 nM. Other transition metals were without effect. Similar effects of purification or addition of DFO on the rate of cysteine oxidation were seen in Tris, glycylglycine, Mops, and Pipes buffers. Catalase decreased the rate of cysteine oxidation, but the sensitivity to iron was similar in the presence and absence of catalase. Copper-catalyzed oxidation of cysteamine and reduced glutathione was much less sensitive to inhibition by iron. Our results offer an explanation for the conflicting literature reports of the effects of chelating agents and catalase on cysteine oxidation, and emphasize the need for buffer purification or addition of DFO in studies concerned with the oxidation or cytotoxicity of this thiol. The exceptional sensitivity of copper-catalyzed cysteine oxidation to iron makes this an attractive system for monitoring the iron content of buffers, and may also have application for determining the free iron content of physiological fluids.
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PMID:Inhibition of copper-catalyzed cysteine oxidation by nanomolar concentrations of iron salts. 1499 Mar 54

Catalase-1, one of four catalase activities of Neurospora crassa, is associated with non-growing cells and accumulates in asexual spores. It is a large, tetrameric, highly efficient, and durable enzyme that is active even at molar concentrations of hydrogen peroxide. Catalase-1 is oxidized at the heme by singlet oxygen without significant effects on enzyme activity. Here we present the crystal structure of catalase-1 at 1.75A resolution. Compared to structures of other catalases of the large class, the main differences were found at the carboxy-terminal domain. The heme group is rotated 180 degrees around the alpha-gamma-meso carbon axis with respect to clade 3 small catalases. There is no co-ordination bond of the ferric ion at the heme distal side in catalase-1. The catalase-1 structure exhibited partial oxidation of heme b to heme d. Singlet oxygen, produced catalytically or by photosensitization, may hydroxylate C5 and C6 of pyrrole ring III with a subsequent formation of a gamma-spirolactone in C6. The modification site in catalases depends on the way dioxygen exits the protein: mainly through the central channel or the main channel in large and small catalases, respectively. The catalase-1 structure revealed an unusual covalent bond between a cysteine sulphur atom and the essential tyrosine residue of the proximal side of the active site. A peptide with the predicted theoretical mass of the two bound tryptic peptides was detected by mass spectrometry. A mechanism for the Cys-Tyr covalent bond formation is proposed. The tyrosine bound to the cysteine residue would be less prone to donate electrons to compound I to form compound II, explaining catalase-1 resistance to substrate inhibition and inactivation. An apparent constriction of the main channel at Ser198 lead us to propose a gate that opens the narrow part of the channel when there is sufficient hydrogen peroxide in the small cavity before the gate. This mechanism would explain the increase in catalytic velocity as the hydrogen peroxide concentration rises.
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PMID:Unusual Cys-Tyr covalent bond in a large catalase. 1534 50

Copper ions are known to inactivate a variety of enzymes, and lactate dehydrogenase (LDH) is exceptionally sensitive to the presence of this metal. We now found that NADH strongly enhances the Cu(II)-mediated loss of LDH activity. Surprisingly, NADH was not oxidized in this process and also NAD+ promoted the Cu(II)-dependent inactivation of LDH. Catalase only partly protected the enzyme, whereas hypoxia even enhanced LDH inactivation. NAD(H) accelerated sulfhydryl (SH) group oxidation of LDH by 5,5-dithio-bis(2-nitrobenzoic acid) (DTNB), and, vice versa, LDH-mediated Cu(II) reduction. LDH activity was preserved by thiol donators and pyruvate and partially preserved by lactate and oxamate. Our results suggest that reactive oxygen species (ROS) are of minor importance for the inactivation of LDH induced by Cu(II)/NADH. We propose that conformational changes of the enzymes' active sites induced by NAD(H)-binding increase the accessibility of active sites' cysteine residues to Cu(II) thereby accelerating their oxidation and, consequently, loss of catalytic activity.
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PMID:NAD(H) enhances the Cu(II)-mediated inactivation of lactate dehydrogenase by increasing the accessibility of sulfhydryl groups. 1587 9

Aging alters cellular responses to both heat and oxidative stress. Thiol-mediated metabolism of reactive oxygen species (ROS) is believed to be important in aging. To begin to determine the role of thiols in aging and heat stress, we depleted liver glutathione (GSH) by administering l-buthionine sulfoximine (BSO) in young (6 mo) and old (24 mo) Fisher 344 rats before heat stress. Animals were given BSO (4 mmol/kg ip) or saline (1 ml ip) 2 h before heat stress and subsequently heated to a core temperature of 41 degrees C over a 90-min period. Liver tissue was collected before and 0, 30, and 60 min after heat stress. BSO inhibited glutamate cysteine ligase (GCL, the rate-limiting enzyme in GSH synthesis) catalytic activity and resulted in a decline in liver GSH and GSSG that was more pronounced in young compared with old animals. Catalase activity did not change between groups until 60 min after heat stress in young BSO-treated rats. Young animals experienced a substantial and persistent reduction in Cu,Zn-SOD activity with BSO treatment. Mn-SOD activity increased with BSO but declined after heat stress. The differences in thiol depletion observed between young and old animals with BSO treatment may be indicative of age-related differences in GSH compartmentalization that could have an impact on maintenance of redox homeostasis and antioxidant balance immediately after a physiologically relevant stress. The significant changes in antioxidant enzyme activity after GSH depletion suggest that thiol status can influence the regulation of other antioxidant enzymes.
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PMID:Aging reduces responsiveness to BSO- and heat stress-induced perturbations of glutathione and antioxidant enzymes. 1594 71

Declines in oxidative and thermal stress tolerance are well documented in aging systems. It is thought that these alterations are due in part to reductions in antioxidant defenses. Although intracellular thiols are major redox buffers, their role in maintaining redox homeostasis is not completely understood, particularly during aging, where the reliance on antioxidant enzymes and proteins may be altered. To determine whether thiol supplementation improved the antioxidant enzyme profile of aged animals after heat stress, young and old Fischer 344 rats were treated with N-acetylcysteine (NAC; 4 mmol/kg ip) 2 h before heat stress. Liver tissue was collected before and 0, 30, and 60 min after heat stress. Aging was associated with a significant decline in tissue cysteine and glutathione (GSH) levels. There was also an age-related decrease in copper-zinc superoxide dismutase activity. Heat stress did not alter liver GSH, glutathione disulfide, or antioxidant enzyme activity. With NAC treatment, old animals took up more cysteine than young animals as reflected in an increase in liver GSH and a corresponding decrease in glutamate cysteine ligase activity. Catalase activity increased after NAC treatment in both age groups. Copper-zinc superoxide dismutase activity did not change with heat stress or drug treatment, whereas manganese superoxide dismutase activity was increased in old animals only. These data indicate that GSH synthesis is substrate limited in old animals. Furthermore, aged animals were characterized by large fluctuations in antioxidant enzyme balance after NAC treatment, suggesting a lack of fine control over these enzymes that may leave aged animals susceptible to subsequent stress.
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PMID:Thiol supplementation in aged animals alters antioxidant enzyme activity after heat stress. 1609 96

Some effects of cadmium exposure (100 microg/L for 4, 8, 12, and 24 h) on the estuarine polychaete Laeonereis acuta (Nereididae) were evaluated. This polychaete was able to accumulate cadmium in the body, with the metal stored mainly in the cytosolic fraction (>10 kDa). Activity of the antioxidant enzymes superoxide dismutase, glutathione S-transferase, and glutathione reductase (GR) as well as the total oxyradical scavenger capacity, the glutamate cysteine ligase catalytic subunit gene expression, and the metallothionein-like proteins content were not affected by cadmium at any exposure time tested. Catalase (CAT) activity, however, was significantly lower (p < 0.05) in worms treated with cadmium compared with that in controls after 8 h of exposure. At the same exposure time, lipid peroxide levels were increased (p < 0.05) in worms exposed to cadmium compared with those in control worms. Interestingly, CAT and GR activities decreased over time (p < 0.05) independent of cadmium treatment, which is a result that could be attributed to starvation. The effects caused by cadmium in the present study were observed only after 8 h of exposure, demonstrating that cadmium can generate oxidative stress.
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PMID:Short-term responses to cadmium exposure in the estuarine polychaete Laeonereis acuta (polychaeta, Nereididae): subcellular distribution and oxidative stress generation. 1670 67

The effect of advanced glycation end products (AGE-s) was studied on the proliferation and cell death of human skin fibroblasts in culture. Several AGE-products were prepared from proteins, a peptide and amino acids, using Glucose or Fructose, with or without Fe2+. The AGE preparations increased cell death at the 7th day, after only 72 hours of incubation. Some of these glycation products modified also proliferation. This effect of AGE-s was even maintained without these products in fresh medium for a second period of incubation up to 10 days from the start of the experiment. In order to explore the role of AGE-receptors, especially of AGE-receptor and of growth factor receptors (fibroblast and epidermal growth factors receptors), antibodies to these receptors were added to cell cultures and their effect on both cell death and proliferation were determined as for the AGE-s. These anti-receptor antibodies imitated to some extent the results obtained with AGE-s, producing increase of cell death and proliferation, followed above a certain concentration of antibodies by a decrease and a new increase or plateau. This might correspond to the internalization of the receptors followed by a re-expression on the cell membrane. The role of receptor-mediated Reactive Oxygen Species-production was also explored using scavengers: N-acetyl-cysteine (NAC), L-Carnosine, superoxide dismutase (SOD) and Catalase. Several of these scavengers decreased cell death, suggesting that Reactive Oxygen Species-production is partially involved in the observed phenomena.
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PMID:Effect of advanced glycation end-products on cell proliferation and cell death. 1691 94

We previously showed that long-term exposure of anterior pituitary cells to nitric oxide (NO) induces apoptosis. The intracellular signals underlying this effect remained unclear. In this study, we searched for possible mechanisms involved in the early stages of the NO apoptotic cascade. Caspase 3 was activated by NO with no apparent disruption of mitochondrial membrane potential. NO caused a rapid increase of reactive oxygen species (ROS), and this increase seems to be dependent of mitochondrial electron transport chain. The antioxidant N-acetyl-cysteine avoided ROS increase, prevented the NO-induced caspase 3 activation, and reduced the NO apoptotic effect. Catalase was inactivated by NO, while glutathione peroxidase (GPx) activity and reduced glutathione (GSH) were not modified at first, but increased at later times of NO exposure. The increase of GSH level is important for the scavenging of the NO-induced ROS overproduction. Our results indicate that ROS have an essential role as a trigger of the NO apoptotic cascade in anterior pituitary cells. The permanent inhibition of catalase may strengthen the oxidative damage induced by NO. GPx activity and GSH level augment in response to the oxidative damage, though this increase seems not to be enough to rescue the cells from the NO effect.
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PMID:Reactive oxygen species are key mediators of the nitric oxide apoptotic pathway in anterior pituitary cells. 1699 55

As a protozoan parasite of hematophagous insects, Trypanosoma rangeli epimastigotes are exposed to reactive oxygen species during development in hosts. In this work, we investigated the role of H(2)O(2) as a modulator of the ecto-phosphatase activity present in living T. rangeli. We observed that H(2)O(2) inhibits ecto-phosphatase activities in the short and long epimastigote forms of T. rangeli. Ecto-phosphatase activity found in the short form was more sensitive than that found in the long form. Moreover, H(2)O(2) inhibited ecto-phosphatase activity of the short form in a dose-dependent manner and this inhibition was reversible after H(2)O(2) removal. This effect was not observed for T. rangeli ecto-ATPase, another ecto-enzyme present on the external surface of T. rangeli. Cysteine, beta-mercaptoethanol, and reduced glutathione were able to revert the enzyme inhibition promoted by H(2)O(2). Catalase and glutathione peroxidase stimulated this ecto-phosphatase activity, whereas superoxide dismutase was not able to modulate this activity. The ecto-phosphatase activity was also activated by FCCP and inhibited by oligomycin. It seems that H(2)O(2) plays a fundamental role in the regulation of cellular processes of these organisms. We showed, for the first time, that these parasites can produce H(2)O(2), and it is able to regulate ecto-phosphatase activity.
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PMID:Modulation of Trypanosoma rangeli ecto-phosphatase activity by hydrogen peroxide. 1938 70


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