Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.6 (catalase)
55,569 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relative levels of reduced glutathione (GSH) have been measured fluorimetrically in individual eggs and early embryos from two mouse strains, one of which shows developmental arrest in vitro. GSH levels fell by approximately 20-25% at fertilization and by approximately 45% by the late 2-cell and early 4-cell stages. No differences were observed between strains or between embryos cultured in vitro or in vivo. Addition of exogenous H2O2 or diethylmaleate depleted GSH. GSH levels were not affected significantly after inhibition of GSH-peroxidase by mercaptosuccinate nor of catalase by aminotriazole. Mercaptosuccinate did not inhibit development but catalase inhibition caused arrest at the 2-cell stage. Addition of exogenous GSH or thioredoxin did not promote development of 'blocking' embryos through the 2-cell block. It is concluded that early embryos lack a mercaptosuccinate sensitive peroxidase activity for removing H2O2, which may be removed by catalase or the glutathione-S-transferase system. It is suggested that GSH may have a role in detoxifying peroxidated lipids. The results are consistent with a role for reactive oxygen species in the 2-cell block.
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PMID:Quantitative analysis of cellular glutathione in early preimplantation mouse embryos developing in vivo and in vitro. 147 14

A comparative study of the antioxidant enzymes superoxide dismutase, catalase, glutathione reductase and thioredoxin reductase was undertaken in two families with xeroderma pigmentosum (XP) and in healthy controls of corresponding skin phototypes. Epidermal blister roofs obtained from the XP patients revealed significant decreases in catalase, thioredoxin reductase, and superoxide dismutase, but glutathione reductase was unaffected. In addition, keratinocytes established from XP patients contained a significantly higher than normal intracellular calcium concentration compared with control cells from a corresponding skin type. Keratinocytes established from an XP obligate heterozygote revealed intermediate levels of calcium between XP homozygotes and controls. Previously high intracellular calcium has been shown to compromise the redox status of keratinocytes by allosteric inhibition of the thioredoxin reductase/thioredoxin electron transfer system. In XP homozygous keratinocytes from sun-exposed epidermis, the intracellular concentration of reduced thioredoxin was decreased to 50% compared with these cells from unexposed skin. Taken together, the results from this study indicate that the epidermis in XP patients lacks effective defense against free radicals and peroxides. In addition to the well-established defect in the normal rates of unscheduled DNA repair, these findings provide an even better explanation for the multiple cutaneous neoplasms in these patients.
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PMID:Defects in antioxidant defense and calcium transport in the epidermis of xeroderma pigmentosum patients. 180 54

Thioredoxin reductase (TR) is a widely distributed flavoenzyme that provides reduced thioredoxin, a dithiol hydrogen donor for protein disulfide reduction and for the reduction of ribonucleotides to deoxyribonucleotides, the first unique step of DNA synthesis. Antitumor quinones were found to exhibit time- and concentration-dependent inhibition of purified rat liver TR that requires the presence of NADPH. Diaziquone initially shows competitive inhibition of the enzyme with 5,5'-dithiobis 2-nitrobenzoic acid as substrate with a Ki of 7.5 microM, which becomes non-competitive after 1 hour incubation with NADPH with a Ki of 0.5 microM. Doxorubicin shows non-competitive inhibition both initially and after 1 hr incubation with NADPH, with Ki values of 10 microM and 0.5 microM, respectively. Electron spin resonance spectroscopy showed the formation of semiquinone free radicals by TR incubated under anaerobic conditions with doxorubicin or diaziquone and NADPH. Redox cycling and formation of oxygen radicals does not play a major role in the inhibition of TR by antitumor quinones as shown by the minor effect on inhibition of removing O2, and the lack of effect of superoxide dismutase and catalase. Diaziquone causes time- and concentration-dependent inhibition of TR activity in intact A204 human rhabdomyosarcoma cells that is associated with growth inhibition. The results suggest that inhibition of TR by antitumor quinones could contribute to their growth inhibitory properties.
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PMID:Inhibition of thioredoxin reductase (E.C. 1.6.4.5.) by antitumor quinones. 216 13

Three different molecular masses (24, 22, and 20 kDa) of antioxidant proteins were purified in Escherichia coli. These proteins exhibited the preventive effects against the inactivation of glutamine synthetase activity and the cleavage of DNA by a metal-catalyzed oxidation system capable of generating reactive oxygen species. Their antioxidant activities were supported by a thiol-reducing equivalent such as dithiothreitol. Analysis of the amino-terminal amino acid sequences and the immunoblots between 24- and 22-kDa proteins indicates that the 24-kDa protein is an intact form of the 22-kDa protein that was previously identified 22-kDa subunit (AhpC) of E. coli alkyl hydroperoxide reductase (AhpC/AhpF). We isolated and sequenced an E. coli genomic DNA fragment that encodes 20-kDa protein. Comparison of the deduced amino acid sequence of the 20-kDa protein with that of AhpC revealed no sequence homology. A search of a data bank showed that the 20-kDa protein is a new type of antioxidant enzyme. The synthesis of this novel 20-kDa protein was increased in response to oxygen stress during growth. The 20-kDa protein resides mainly in the periplasmic space of E. coli, whereas the 24-kDa AhpC resides mainly in the matrix. The 20-kDa protein was functionally linked to the thioredoxin as an in vivo thiol-regenerating system and exerted a peroxidase activity. This 20-kDa protein is thus named "thiol peroxidase," which could act as an antioxidant enzyme removing peroxides or H2O2 within the catalase- and peroxidase-deficient periplasmic space of E. coli.
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PMID:Thioredoxin-linked "thiol peroxidase" from periplasmic space of Escherichia coli. 749 81

Adult T cell leukemia-derived factor (ADF), originally defined as an interleukin 2 receptor/alpha (alpha) chain inducer produced by human T-lymphotropic virus type-I transformed cells, is identical to human thioredoxin (TRX). In this study, the protective effect of ADF/TRX on the cytotoxicity of endothelial cells caused by phorbol myristate acetate (PMA)-activated neutrophils or hydrogen peroxide (H2O2) was examined. When murine endothelial F-2 cells established from an ultraviolet light-induced tumor on a nude mouse were incubated with PMA-activated neutrophils or with 1 mM H2O2 for 6 hours, the cytotoxicity of F-2 cells was respectively 51 +/- 4% or 40 +/- 8% by the 51Cr releasing assay. Recombinant ADF/TRX (rADF/TRX) inhibited this cytotoxicity in a dose-dependent manner, although mutant ADF/TRX (cysteine 31 to serine), 2-mercaptoethanol and dithiothreitol did not. On a molar basis, rADF/TRX was more effective than glutathione but less effective than catalase. Immunoblotting analysis showed that treatment with 0.1 mM H2O2 induced murine TRX on F-2 cells. These findings indicate that ADF/TRX is an oxidative stress-inducible endogenous protein and rADF/TRX plays a protective role against activated neutrophils- or H2O2-induced endothelial cytotoxicity.
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PMID:Adult T cell leukemia-derived factor/human thioredoxin protects endothelial F-2 cell injury caused by activated neutrophils or hydrogen peroxide. 782 34

A large body of evidence indicates that AIDS may be the consequence of a virus-induced antioxidant deficiency and implicates reactive oxygen species (ROS) in the pathogenesis of HIV infection. The high level of antigenic acid and cytokines activities in AIDS results in the production of superoxides (O2-), hydrogen peroxide (H202) and hydroxyl radicals (OH). HIV-infected T cells display low levels of SOD, catalase, thioredoxin and glutatione peroxidase rendering them susceptible to undergo apoptosis. Induction of NF kappa B and HIV replication are at least in part dependent on reactive oxygen intermediates. We examined the protective effects of two antioxidants. Ferulic Acid (FA) and Ethyl Ferulate (EF) at 1, 5, 10, 10 microM on the TNF induced HIV activation in the chronically infected promonocytic U1 cell line. FA and EF at 5 microM elicit a marked decrease of HIV p24 release. HIV inhibition was greater after pretreatment with EF than with FA. At these concentrations, no cytotoxicity was observed. When SOD (100 UI) was combined with EF and FA no more inhibition was observed. But when SOD was added alone, it induced a marked inhibition (30%). This class of drugs may present potential interest as antiviral agents or as adjuvant therapy in AIDS.
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PMID:[Effect of the liposolubility of free radical scavengers on the production of antigen P24 from a HIV infected monocytic cell line]. 852 Oct 85

The thiol-specific antioxidant protein (TSA) protects glutamine synthetase from inactivation by a metal-catalyzed oxidation (MCO) system comprised of dithiothreitol (DTT)/Fe3+/O2 but not by the ascorbate/Fe3+/O2 MCO system. The removal of sulfur-centered radicals or H2O2 has been proposed as the protective mechanism of TSA. Like catalase, TSA prevents the initiation of the rapid O2 uptake phase during MCO of DTT but causes only partial inhibition when added after the reaction is well into the propagation phase. Stoichiometric studies showed that the antioxidant property of TSA is, at least in part, due to its ability to catalyze the destruction of H2O2 by the overall reaction 2 RSH + H2O2 --> RSSR + H2O. Results of kinetic studies demonstrate that the removal of H2O2 by TSA correlates with its ability to protect glutamine synthetase from inactivation. In the presence of thioredoxin, TSA is more active, whereas C170S (an active mutant of TSA in which cysteine 170 was replaced by a serine) and open reading frame 6 (a human antioxidant protein homologous to TSA with only one conserved cysteine residue) are only slightly affected. The thiol specificity of the protective activity of TSA derives from the fact that the oxidized form of TSA can be converted back to its sulfhydryl form by treatment with thiols but not by ascorbate.
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PMID:Removal of hydrogen peroxide by thiol-specific antioxidant enzyme (TSA) is involved with its antioxidant properties. TSA possesses thiol peroxidase activity. 866 80

Adult T cell leukemia-derived factor (ADF) is a human thioredoxin (Trx) and is a disulfide reducing protein with various biological functions. We found that expression of the ADF/Trx gene was increased by oxidative agents such as hydrogen peroxide, diamide and menadione in Jurkat cells. Analysis using a CAT expression vector plasmid under the control of the ADF/Trx gene promoter revealed that CAT gene expression in Jurkat cells was increased after exposure to oxidative agents. A series of deletion analyses showed that a region from -976 to -890 of the 5' flanking sequence was required for enhancement of ADF/Trx promoter activity against the oxidative agents. Gel mobility shift assay revealed the specific DNA binding activities to the sequences from -953 to -930 in the nuclear extracts from the Jurkat cells. The sequences in this region showed no homology with any known consensus sequences for DNA binding factors. It is suggested that ADF/Trx gene expression is enhanced through a novel cis-acting regulatory element responsive for the oxidative stress and a new factor(s) is involved in this oxidative stress responsive element.
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PMID:A novel promoter sequence is involved in the oxidative stress-induced expression of the adult T-cell leukemia-derived factor (ADF)/human thioredoxin (Trx) gene. 875 6

Adult T-cell leukemia-derived factor (ADF), identified in the supernatant of adult T-cell leukemia (ATL) cell culture, is a human homologue of thioredoxin and consists of 104 amino acids; it has two redox-active half-cysteine residues in an exposed active center. Human thioredoxin has many biological activities, including growth promotion, cell activation, and a catalase-like radical scavenging activity. We examined the protective effect of human thioredoxin (h-thioredoxin) against reperfusion-induced arrhythmias in an isolated rat heart model with 10-min regional ischemia followed by 30-min reperfusion. Male Wistar rats were assigned to six groups: a control, a superoxide dismutase (SOD 8 x 10(4) IU/L), and a catalase group (1 x 10(6) IU/L), and three groups treated with h-thioredoxin [approximately .01 microM (TRX-I group), approximately 0.1 microM (TRX-II group), and approximately 1 microM (TRX-III group)]. In the early reperfusion period, h-thioredoxin reduced the incidence of ventricular fibrillation (VF) to 8% in the TRX-II group (p < 0.01) from the control value of 75%. SOD and catalase reduced the incidence of VF to 43 and 33%, respectively (NS). During the entire reperfusion period, the incidence of VF in the SOD group was 79%, as compared to 83% in the control group. In the catalase and TRX-II groups, the incidence of VF was significantly reduced to 42 and 25%, respectively. These findings indicate that SOD failed to protect against the reperfusion-induced arrhythmias. h-Thioredoxin exerted a protective effect against these arrhythmias; a concentration of approximately 0.1 micro was the most effective.
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PMID:Protection against reperfusion-induced arrhythmias by human thioredoxin. 885 44

Thiol compounds, such as L-cysteine and glutathione (GSH), play crucial roles in the regulation of lymphocyte proliferation. In this study, we analyzed the effect of L-cystine and GSH depletion on lymphocyte survival and investigated the regulatory roles of adult T cell leukemia (ATL)-derived factor (ADF)/human thioredoxin (hTRX) in relation to these low m.w. thiols. MT-1, MT-2, and Jurkat cells underwent apoptosis when cultured in the L-cystine- and GSH-free medium within 18 to 24 h. Dichlorofluorescin oxidation assay indicated that the apoptosis in MT-1 and MT-2 cells was preceded by an increase in the level of intracellular hydrogen peroxide (H2O2). The addition of catalase and recombinant ADF/hTRX (rADF) partially blocked the apoptosis in a dose-dependent manner. rADF has been also shown to enhance the internalization of L-cystine into MT-2 cells in a dose-dependent manner, whereas oxidized rADF or mutated rADF that has no insulin-reducing activity failed to do so. Furthermore, culture in the L-cystine- and GSH-free medium lowered the cellular GSH content of PHA blasts, which was restored dose-dependently by rADF. These data suggest that the inability to neutralize oxidative stress results in the apoptosis of lymphoid cells under L-cystine- and GSH-depleted conditions. The protective effects of rADF may be explained by direct scavenging action on H2O2 (catalase-like activity) or by indirect neutralizing effects on the pro-oxidant status through enhancing the L-cystine internalization and elevating the intracellular GSH content.
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PMID:Adult T cell leukemia (ATL)-derived factor/human thioredoxin prevents apoptosis of lymphoid cells induced by L-cystine and glutathione depletion: possible involvement of thiol-mediated redox regulation in apoptosis caused by pro-oxidant state. 912 Feb 63


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