Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30044 (antioxidant enzyme)
 8,037 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thioredoxin reductase (TRR), a member of the pyridine nucleotide-disulfide oxidoreductase family of flavoenzymes, undergoes two sequential thiol-disulfide interchange reactions with thioredoxin during catalysis. In order to assess the catalytic role of each nascent thiol of the active site disulfide of thioredoxin reductase, the 2 cysteines (Cys-136 and Cys-139) forming this disulfide have been individually changed to serines by site-directed mutageneses of the cloned trxB gene of Escherichia coli. Spectral analyses of TRR(Ser-136,Cys-139) as a function of pH and ionic strength have revealed two pKa values associated with the epsilon 456, one of which increases from 7.0 to 8.3 as the ionic strength is increased, and a second at 4.4 which is seen only at high ionic strength. epsilon 458 of wild type TRR(Cys-136,Cys-139) and epsilon 453 of TRR(Cys-136,Ser-139) are pH-independent. A charge transfer complex (epsilon 530 = 1300 M-1 cm-1), unique to TRR(Ser-136,Cys-139), has been observed under conditions of high ammonium cation concentration (apparent Kd = 54 microM) at pH 7.6. These results suggest the assignment of Cys-139 as the FAD-interacting thiol in the reduction of thioredoxin by NADPH via thioredoxin reductase. If, as with other members of this enzyme family, the two distinct catalytic functions are each carried out by a different nascent thiol, then Cys-136 would perform the initial thiol-disulfide interchange with thioredoxin. Steady state kinetic analyses of the proteins have revealed turnover numbers of 10 and 50% of the value of the wild type enzyme for TRR(Ser-136,Cys-139) and TRR(Cys-136,Ser-139), respectively, and no changes in the apparent Km values of TR(S2) or NADPH. The finding of activity in the mutants indicates that the remaining thiol can carry out interchange with the disulfide of thioredoxin, and the resulting mixed disulfide can be reduced by NADPH via the flavin.
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PMID:Characterization of two active site mutations of thioredoxin reductase from Escherichia coli. 264 68

Epidemiologists have observed a positive association between human morbidity and mortality and the atmospheric concentrations of fine particulate matter (PM), but the mechanisms underlying the toxic effects of PM have not been elucidated. Various components of ambient PM have been implicated in toxicity (including ultrafine particles, transition metals, organics and oxidants). Our research focused on hydrogen peroxide (H2O2). We speculated that fine PM transports H2O2 into the lower lung, leading to tissue injury and to accumulation and activation of macrophages in these regions. The macrophages release cytotoxic mediators and proinflammatory cytokines that contribute to the pathogenesis of tissue injury. To test this hypothesis, we conducted studies to determine (1) whether tissue injury induced by aerosols is mediated by cytotoxic H2O2 carried into the lower lung by fine particles and (2) whether exposure of rats to fine PM leads to accumulation of activated macrophages in the lung. For our studies, systems were designed to generate model atmospheric fine PM and atmospheric peroxides consisting of an ammonium sulfate [(NH4)2SO4] aerosol (mass median diameter, 0.46 +/- 0.14 microm) and H2O2. We also constructed a 6-port nose-only exposure chamber. Female Sprague Dawley rats were exposed for 2 hours to aerosols consisting of (NH4)2SO4 (430 microg/m3), (NH4)2SO4 + 10, 20 or 100 ppb H2O2, vapor-phase H2O2 (10, 20 or 100 ppb), or particle-free air. Studies using oxygen-18 (18O)-labeled H2O2 were conducted to validate the transport of H2O2 into the lower lung with (NH4)2SO4. Rats were killed immediately (0 hours) or 24 hours after exposure. Compared with control animals, inhalation of (NH4)2SO4 and H2O2, alone or in combination, had no major effect on cell number or viability, protein content, or lactate dehydrogenase (LDH) levels in bronchoalveolar lavage (BAL) fluid collected either immediately or 24 hours after exposure. However, electron microscopy revealed that a larger number of neutrophils in pulmonary capillaries adhered to the vascular endothelium, especially in lungs of rats exposed to (NH4)2SO4 + H2O2. Inhalation of (NH4)2SO4 + H2O2 was also found to be associated with altered macrophage functional activity. Thus, exposing rats to (NH4)2SO4 + 20 ppb H2O2 or 20 ppb H2O2 alone caused a level of tumor necrosis factor alpha (TNF-alpha) production by lung macrophages that was higher than in controls. This higher level was observed immediately after exposure and persisted for at least 24 hours. Greater TNF-alpha production was also detected 24 hours after exposure to (NH4)2SO4 + 10 ppb H2O2. Immediately after rats inhaled (NH4)2SO4 + 10 ppb H2O2 or 20 ppb H2O2 alone, we also observed a transiently higher production of superoxide anion (O2-) by alveolar macrophages. Macrophages isolated 24 hours after exposure to 20 ppb H2O2 also produced larger quantities of superoxide anion. In contrast, immediately after exposure, macrophages from rats exposed to (NH4)2SO4 + 10 ppb H2O2 or to 20 ppb H2O2 alone generated less nitric oxide (NO). Reduced nitric oxide production was also observed 24 hours after exposure to (NH4)2SO4 + 10 ppb H2O2 or to 10 or 20 ppb H2O2 alone. Reduced nitric oxide production may have been due to superoxide anion-driven formation of peroxynitrite (ONOO-) anions. In this regard, nitrotyrosine, an in vivo marker of peroxynitrite, was detected in lung tissue immediately after rats were exposed to (NH4)2SO4 + H2O2 or to H2O2 alone (10 or 20 ppb). We also found that alveolar macrophages from rats exposed to (NH4)2SO4 + H2O2 showed a greater expression of the antioxidant enzyme heme oxygenase-1 (HO-1) when stimulated with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Similar results were observed after exposure of rats to an organic peroxide aerosol (cumene hydroperoxide). Taken together, the results of our studies demonstrate that biological effects of inhaled H2O2 are augmented by fine PM. Moreover, tissue injury induced by (NH4)2SO4 + H2O2 may be related to altered production of cytotoxic mediators by alveolar macrophages. Determining the relevance of these toxicologic results to human health will be important in future studies for evaluating the risk of exposure.
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PMID:Peroxides and macrophages in the toxicity of fine particulate matter in rats. 1503 94

Thioredoxin reductase (TrxR), an enzyme belonging to the flavoprotein family of pyridine nucleotide-disulfide oxidoreductases, was isolated from the deoxycholate-soluble extract of the common liver fluke, Fasciola hepatica. Purification to homogeneity of the 60-kDa enzyme from the adult worm was achieved by a combination of ammonium sulfate fractionation, anion exchange, and affinity chromatography on 2',5'-adenosine diphosphate-Sepharose. Using the 5,5'-dithiobis(2-nitrobenzoic acid) assay, the purified TrxR showed a specific activity of 7,117 U min(-1) mg(-1). The enzyme activity was completely inhibited by the presence of the gold compound aurothioglucose (IC50 = 120 nm), indicating that F. hepatica TrxR is a selenoenzyme. Also, the enzyme was capable of reducing disulfide bonds in insulin and was activated by the presence of the reduced form of flavin adenine dinucleotide, properties shared with mammalian TrxRs. Furthermore, the isolated enzyme showed very low glutaredoxin (Grx) activity (0.47 U mg(-1)), but no glutathione reductase activity was detected. Affinity-purified IgGs (20 microg ml(-1)) from the antisera produced against the purified TrxR inhibited its activity about 80% with respect to the control. The enzyme was immunolocalized in cells located within the parenchyma and in the testes, but it was not found in the tegument of the adult fluke.
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PMID:Purification, characterization, and immunolocalization of a thioredoxin reductase from adult Fasciola hepatica. 1516 39

The aim of this study was to investigate effect of antiemetics on G6PD and antioxidant enzymes. Antiemetics are currently being used to reduce or prevent nausea and vomiting in patients. This is the first study to show effect of antiemetics on glucose-6-phosphate dehydrogenase (G6PD) and antioxidant enzyme activities. For in vitro studies, G6PD was purified from human erythrocyte, 10, 26-fold in a yield of 51.3% by using ammonium sulphate precipitation and 2',5'-ADP-Sepharose 4B affinity gel. The purified enzyme showed a single band on sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE). The effects of four different antiemetics (granisetron hydrochloride, ondansetron hydrochloride, metoclopramide hydrochloride, trimethobenzamide hydrochloride) were investigated on the purified enzyme. Granisetron hydrochloride and ondansetron hydrochloride inhibited the enzyme activity (Ki values; 5.05 mM and 0.034 mM, I50 values; 3.9 mM and 0.036 mM, respectively). Metoclopramide hydrochloride, trimethobenzamide hydrochloride showed no inhibition effects. In addition, in vivo studies, effects of ondansetron hydrochloride on the G6PD, glutathione reductase (GR), glutathione peroxidase (GPx) and catalase (CAT) were examined in the rat erythrocytes. G6PD (49% of control), GR (55% of control), CAT (60% of control) activities in erythrocytes were significantly decreased whereas GPx (183% of control) was significantly increased. A marked alteration in these enzymes may be result of oxidative stress in the rats receiving ondansetron hydrochloride.
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PMID:Effects of antiemetic drugs on glucose 6-phosphate dehydrogenase and some antioxidant enzymes. 1545 70

Corticosteroids are anti-inflammatory drugs that are similar to the natural corticosteroid hormones produced by the cortex of the adrenal glands. The objective of this study was to scrutinize effects of some corticosteroids on glucose-6-phosphate dehydrogenase (G6PD) and some antioxidant enzymes. Initially, G6PD was purified from human erythrocytes by using ammonium sulphate precipitation and affinity chromatography. The two drugs, dexamethasone phosphate and prednisolone, investigated on the purified enzyme inhibited the enzyme activity. Comparative in vivo studies were performed to determine the effects of dexamethasone phosphate on the antioxidant enzyme activities using Spraque-Dawley rats. G6PD and catalase (CAT) activities were found significantly lower than in the control, whereas glutathione peroxidase (GP) activity was significantly increased in the erythrocytes of rats the receiving drug; glutathione reductase (GR) activity was unaffected. The results imply that dexamethasone phosphate may affect oxidative stress by changing antioxidant enzyme activities.
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PMID:Evaluation of effect of some corticosteroids on glucose-6-phosphate dehydrogenase and comparative study of antioxidant enzyme activities. 1589 80

The activities of antioxidant enzymes viz. glutathione reductase, GR; superoxide dismutase, SOD; peroxidase, POD; catalase, CAT and glutathione-S-transferase, GST and alkaloid accumulation were investigated in leaf pairs (apical, middle, basal) and in roots of Catharanthus roseus seedlings under the conditions of different nitrogen sources (20 mM KNO(3) and 2 mM NH(4)Cl) and salinity, in the absence (non-saline control) and in the presence of 100 mM NaCl in the nutrient solution. Salinity caused a reduction in plant biomass. The biomass production of ammonium-fed plants was lower than that of nitrate-fed plants. The antioxidant enzymes exhibited higher activity in saline-treated plants. Changes in antioxidant enzyme activity caused by different nitrogen sources differed in all leaf pairs, as well as in roots of C. roseus. Ammonium-fed plants showed higher CAT, GR and GST activity in leaf pairs as well as in roots, while POD and SOD activity were higher in nitrate-fed plants. Higher peroxidase activity concomitant with the increased accumulation of alkaloid was found in all leaf pairs, as well as in roots of C. roseus of NO(3)(-) fed plants as compared to NH(4)(+) fed plants.
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PMID:Effect of salinity and different nitrogen sources on the activity of antioxidant enzymes and indole alkaloid content in Catharanthus roseus seedlings. 1636 Jul 99

Deinococcus radiodurans, a Gram-positive bacterium capable of withstanding extreme ionizing radiation, contains two thioredoxins (Trx and Trx1) and a single thioredoxin reductase (TrxR) as part of its response to oxidative stress. Thioredoxin reductase is a member of the family of pyridine nucleotide-disulfide oxidoreductase flavoenzymes. Recombinant D. radiodurans TrxR with a His tag at the N-terminus was expressed in Escherichia coli and purified by metal-affinity chromatography. The protein was crystallized using the sitting-drop vapour-diffusion method in the presence of 35% PEG 4000, 0.2 M ammonium acetate and citric acid buffer pH 5.1 at 293 K. X-ray diffraction data were collected on a cryocooled crystal to a resolution of 1.9 angstroms using a synchrotron-radiation source. The space group was determined to be P3(2)21, with unit-cell parameters a = b = 84.33, c = 159.88 angstroms. The structure of the enzyme has been solved by molecular-replacement methods and structure refinement is in progress.
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PMID:Expression, purification, crystallization and preliminary X-ray crystallographic studies of Deinococcus radiodurans thioredoxin reductase. 1688 May 49

In this paper, submersed plant Hydrilla verticillata was cultivated in a 1/10 Hoagland culture medium added with different concentration NH4 + -N (0, 0. 5, 2. 0, 4. 0 mg x L(-1)) and 10 mg x L(-1) cadmium to study the effects of NH4 + -N on H. verticillata growth and its antioxidant enzyme system under Cd stress, and approach the degradation mechanism of submersed macrophyte in eutrophic and polluted water bodies. The results showed that under 10 mg x L(-1) Cd stress, the chlorophyll content of H. verticillata decreased obviously, and SOD and POD activities increased first but declined then. NH4 + -N accelerated the stress effect of Cd. Under 0. 5 h joint stress of Cd and NH4 + -N, SOD activity increased significantly, while such an increase needed 3 hours under single Cd stress. Relative to chlorophyll and protein, antioxidant enzyme system was an early sensitive index, and SOD was more sensitive than POD. After two days exposure to Cd plus NH4 -N, H. verticillata was mainly stressed by Cd, and NH4+ -N stress could be neglected.
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PMID:[Effects of different concentration ammonium-n on Hydrilla verticillata antioxidant enzymes under Cd stress]. 1745 Jul 50

Glutathione peroxidase 3 (Gpx3) is ubiquitously expressed and is important antioxidant enzyme in yeast. It modulates the activities of redox-sensitive thiol proteins, particularly those involved in signal transduction pathway and protein translocation. Through immunoprecipitation/two-dimensional gel electrophoresis (IP-2DE), MALDI-TOF mass spectrometry, and a pull down assay, we found glutamine synthetase (GS; EC 6.3.1.2) as a candidate interacting protein with Gpx3. GS is a key enzyme in nitrogen metabolism and ammonium assimilation. It has been known that GS is non-enzymatically cleaved by ROS generated by MFO (thiol/ Fe(3+)/O(2) mixed-function oxidase) system. In this study, it is demonstrated that GS interacts with Gpx3 through its catalytic domain both in vivo and in vitro regardless of redox state. In addition, Gpx3 helps to protect GS from inactivation and degradation via oxidative stress in an activity-independent manner. Based on the results, it is suggested that Gpx3 protects GS from non-enzymatic proteolysis, thereby contributing to cell homeostasis when cell is exposed to oxidative stress.
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PMID:Glutathione peroxidase 3 of Saccharomyces cerevisiae suppresses non-enzymatic proteolysis of glutamine synthetase in an activity-independent manner. 1770 71

Peroxidases (EC 1.11.1.7; donor: hydrogen peroxide oxidoreductase) are part of a large group of enzymes. In this study, peroxidase, a primer antioxidant enzyme, was purified with 19.3 fold and 0.2% efficiency from cauliflower (Brassica oleracea L.) by ammonium sulphate precipitation, dialysis, CM-Sephadex ion-exchange chromatography and Sephadex G-25 purification steps. The substrate specificity of peroxidase was investigated using 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulphonic acid) (ABTS), 2-methoxyphenol (guaiacol), 1,2-dihydroxybenzene (catechol), 1,2,3-trihyidroxybenzene (pyrogallol) and 4-methylcatechol. Also, optimum pH, optimum temperature, optimum ionic strength, stable pH, stable temperature, thermal inactivation conditions were determined for guaiacol/H(2)O(2), pyrogallol/H(2)O(2), ABTS/H(2)O(2), catechol/H(2)O(2) and 4-methyl catechol/H(2)O(2) substrate patterns. The molecular weight (M(w)) of this enzyme was found to be 44 kDa by gel filtration chromatography method. Native polyacrylamide gel electrophoresis (PAGE) was performed for isoenzyme determination and a single band was observed. K(m) and V(max) values were calculated from Lineweaver-Burk graph for each substrate patterns.
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PMID:Purification and characterization of peroxidase from cauliflower (Brassica oleracea L. var. botrytis) buds. 1847 41


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