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:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine if non-selenium-dependent glutathione peroxidase (Non-Se GSH-Px) activity is present in rat lung, we fractionated rat lung soluble fractions from rats fed a selenium-deficient or control diet and measured glutathione peroxidase activity with both cumene hydroperoxide and hydrogen peroxide as substrates. We also measured glutathione S-transferase (GSH S-transferase) activity in the fractions with 1-chloro-2,4-dinitrobenzene as substrate. Non-Se GSH-Px activity was present (about 34% of total GSH-Px activity), and the peak present in the gel filtration chromatogram coeluted with the GSH S-transferase peak. We then measured GSH S-transferase activity in lung-soluble fractions from rats exposed to room air or 85% O2 for 5 days. Lung GSH S-transferase activity was increased in the oxygen-exposed animals when compared to the air-exposed controls. The increase in GSH S-transferase activity could represent the induction of lung non-Se GSH-Px activity.
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PMID:Non-selenium-dependent glutathione peroxidase activity in rat lung: association with lung glutathione S-transferase activity and the effects of hyperoxia. 685 74

Reduced glutathione (GSH) and activity of GSH related enzymes play a key role in defence against oxygen free radicals, whose production is, as known, raised in patients affected by diabetes mellitus, and at the same time they may contribute to the process of platelet aggregation. The purpose of this study was to evaluate GSH levels and activity of glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-Red), glutathione transferase (GSH-Tr), glucose-6-phosphate-dehydrogenase (G6PDH), and thioltransferase (TT) in platelets of insulin-dependent diabetic patients in fair metabolic control (mean glycated haemoglobin: 6.5%), as related to presence of retinopathy, neuropathy or nephropathy and to platelet aggregation by arachidonic acid (AA) in vitro. Mean effective dose (ED50) of AA was on average significantly lower in the group of insulin-dependent diabetic patients (0.41 +/- 0.02 mM (SEM), n = 46) as compared with that of control subjects strictly matched for age, sex and weight (0.77 +/- 0.02, n = 51; P = 0.0001). Mean platelet GSH as well as the activity of GSH related enzymes expressed as geometric mean (95% confidence intervals) were similar in diabetic patients and in controls, except for GSSG-Red whose activity was significantly higher in diabetic subjects (28.5 (14.4-57.5) mU 10(-9) platelets vs. 20.3 (8.7-56) mU 10(-9) platelets; P = 0.01). In the diabetic group TT was reduced when compared with healthy controls (3.8 (0.9-12.2) mU 10(-9) platelets vs. 6 (1.6-26.1) mU 10(-9) platelets; P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glutathione, glutathione utilizing enzymes and thioltransferase in platelets of insulin-dependent diabetic patients: relation with platelet aggregation and with microangiopatic complications. 749 40

During arousal from estivation oxygen consumption by land snails (Otala lactea) increases severalfold. To determine whether snails prepared for an accompanying rise in the rates of oxyradical generation by altering their antioxidant defense mechanisms, changes in the activities of antioxidant enzymes and lipid peroxidation products were quantified in foot and hepatopancreas of control, 30-day estivating, and aroused snails. Compared with controls, estivating O. lactea showed significant increases in the activities of foot muscle superoxide dismutase (SOD) (increasing by 56-67%), catalase (51-72%), and glutathione S-transferase (79-108%), whereas, in hepatopancreas, SOD (57-78%) and glutathione peroxidase (93-144%) increased. Within 40 min after arousal began, hepatopancreas glutathione peroxidase activity had returned to control values, but SOD showed a further 70% increase in activity but then returned to control levels by 80 min. Estivation had no effect on total glutathione (GSH + 2 GSSG) concentrations in tissues, but GSSG content had increased about twofold in both organs of 30-day dormant snails. Lipid peoxidation (quantified as thiobarbituric acid reactive substances) was significantly enhanced at the onset of arousal from dormancy, indicating that oxidative stress and tissue damage occurred at this time. The data suggest that antioxidant defenses in snail organs are increased while snails are in the hypometabolic state as a preparation for oxidative stress during arousal.
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PMID:Antioxidant defenses and metabolic depression in a pulmonate land snail. 761 13

Experimental data indicate that active oxygen species may be casually involved in the development of asbestos-related disease. Thus, it was hypothesized that individual differences in glutathione transferase activity, which may affect the ability to inactivate molecules formed in relation to oxidative stress, could influence the biological response to asbestos exposure. We could, however, not demonstrate an increased risk for radiographic changes or reduced lung function among asbestos cement workers deficient for glutathione transferase theta (GSTT1), glutathione transferase mu (GSTM1), or having a combined deficiency of enzyme activity.
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PMID:Radiographic changes and lung function in relation to activity of the glutathione transferases theta and mu among asbestos cement workers. 761 63

Both radiation and anthracycline antibiotics may produce reactive oxygen species to cause cytotoxicity, and it has been suggested that some cellular antioxidant enzymes may be important for resistance to these agents. The human breast adenocarcinoma cell line MCF-7WT has a low level of glutathione peroxidase (GPX) activity. We have transfected MCF-7WT cells with a plasmid that contains the cDNA for human GPX under the transcriptional control of the human metallothionein IIA promoter. One transfected clone, MCF-GPX-6, contained multiple copies of GPX cDNA/cell and, after exposure to heavy metals, expressed a level of GPX enzyme activity that was 40-fold higher than that present in MCF-7WT cells and comparable to the GPX activity contained in the doxorubicin-resistant MCF-7DOX cell line. No differences in levels of glutathione, catalase, superoxide dismutase, glutathione S-transferase, or glutathione reductase were noted in MCF-GPX-6 cells compared to MCF-7WT cells. MCF-GPX-6 cells were relatively resistant to hydrogen peroxide and tert-butylhydroperoxide compared to MCF-7WT cells, e.g., exposure of both cell lines to 750 microM H2O2 for 1 h resulted in a relative surviving fraction of 0.07 for MCF-7WT and 0.35 for MCF-GPX-6 cells. However, no difference in sensitivity to either radiation or doxorubicin was noted between MCF-7WT and MCF-GPX-6 cells. These results suggest that GPX is not important for the development of cellular resistance to either radiation or doxorubicin.
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PMID:Enhanced glutathione peroxidase expression protects cells from hydroperoxides but not from radiation or doxorubicin. 767 Dec 61

Although the mechanisms responsible for chemically induced oxidative stress are under intense investigation, little is known about the effects of prooxidant chemicals on the expression of drug-metabolizing enzymes. We examined the effects of diquat (0.1 mmol/kg, ip) and ciprofibrate (0.025% w/w, diet), chemicals which induce oxidative stress via different biochemical mechanisms, on the steady-state messenger RNA (mRNA) levels of six cytochrome P450 enzymes, seven glutathione S-transferase (GST) isoenzymes, UDP-glucuronosyl transferase 1-06 (UGT1*06), gamma-glutamylcysteine synthetase (gamma GCS), NADP(H):quinone oxidoreductase (quinone reductase), Cu/Zn superoxide dismutase (SOD), catalase, and 18S ribosomal RNA in the livers of male Sprague-Dawley rats. Effects of chemical treatments on mRNA levels were compared to changes in catalytic activities for selected enzymes. Ciprofibrate treatment selectively decreased CYP1A2 mRNA expression, whereas both chemicals suppressed CYP3A2 mRNA expression. CYP4A1 mRNA expression and lauric acid hydroxylase activities were induced by ciprofibrate treatment, whereas diquat treatment moderately increased CYP4A1 mRNA levels without affecting lauric acid hydroxylase activities. The steady-state mRNA levels encoding constitutively expressed GST isozymes (Ya1, Ya2, Yb1, Yb2, and Yc1) were decreased by diquat exposure, and the mRNA encoding four of the five constitutively expressed GSTs (Ya1, Ya2, Yb1, and Yc1) were also decreased by ciprofibrate treatment. Nonconstitutively expressed or low constitutively expressed genes (CYP1A1, CYP2B1, CYP2B2, GST Yc2, GST Yf, and UGT1*06) were not induced by exposure to the prooxidants. Changes in isozyme-specific catalytic activities were more consistent with the observed changes in mRNA expression for the GSTs than for the P450s. Both treatments had inhibitory effects on hepatic GSH biosynthesis by decreasing gamma GCS large-subunit mRNA expression, gamma GCS catalytic activities, and hepatic GSH concentrations. Cu/Zn SOD and quinone reductase mRNA levels were increased after ciprofibrate exposure, whereas Cu/Zn SOD mRNA expression was decreased in the diquat-treated animals. The results of this study indicate that diquat and ciprofibrate can decrease the expression profile of a number of phase I, phase II, and antioxidant enzymes and inhibit GSH biosynthesis. These effects may involve the pretranslational loss of hepatic mRNAs, possibly due to accelerated production of reactive oxygen species.
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PMID:The effects of diquat and ciprofibrate on mRNA expression and catalytic activities of hepatic xenobiotic metabolizing and antioxidant enzymes in rat liver. 767 60

Oxygen-derived free radicals have been implicated in the pathogenesis of ulcerative colitis. Mammalian tissues contain antioxidant systems that offer protection from the damaging effect of these active species. In the present study, the activity of the antioxidant enzymes catalase, glutathione peroxidase, glutathione transferase and glutathione reductase were measured in rectal biopsies from patients with ulcerative colitis and compared with that obtained from normal subjects. A significant decrease in the activity of glutathione transferase was observed in ulcerative colitis (48.32 +/- 6.73 units/mg protein, mean +/- s.e.) compared to normal (68.20 +/- 6.83; P = 0.015). There was no difference in the activity of other antioxidant enzymes between controls and ulcerative colitis. Myeloperoxidase, a marker for neutrophil infiltration, was considerably increased in ulcerative colitis while malonaldehyde, the end product of lipid peroxidation, was not increased. The reduced activity of glutathione transferase in ulcerative colitis may be an additional factor in the pathogenesis of mucosal damage in this disease.
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PMID:Colonic mucosal antioxidant enzymes and lipid peroxide levels in normal subjects and patients with ulcerative colitis. 778 69

A triple mutant of rat liver glutathione S-transferase 3-3 that has all three cysteine residues replaced with serine (CallS) and a quadruple mutant with a Tyr-115 to phenylalanine substitution on CallS (CallSY115F) were reacted with 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone (GS-1,4-TCBQ). The modified proteins were analysed on a triple-quadrupole mass spectrometer equipped with an electrospray ionization source. At an enzyme: GS-1,4-TCBQ ratio of 1:10, the enzymes were modified at multiple sites. Covalent attachment of a single inhibitor on to the protein was achieved by lowering the enzyme: GS-1,4-TCBQ ratio to 1:1. Results from m.s. analyses suggest that the inhibitor on the CallSY115F mutant exists as a glutathionyl dichlorobenzoquinone derivative. The modifiers of the CallS mutants are glutathionyl monochlorobenzoquinone derivatives. Therefore, GS-1,4-TCBQ reacts at a single site on CallSY115F, but probably cross-links two regions on wild-type and CallS mutant. To confirm our observation, CallS was modified with 1-chloro2,4-dinitrobenzene, which specifically labels Tyr-115, before reacting with GS-1,4-TCBQ. The inhibitor formed a glutathionyl dichlorobenzoquinone adduct on the dinitrophenyl-CallS mutant. In addition, the benzoquinone derivative on the protein can be partially removed by 1-chloro-2,4-dinitrobenzene. Peptide mapping and sequencing analysis of the GS-1,4-TCBQ-modified CallS mutant revealed that the C-terminal 16-amino-acid fragment is labelled. Molecular modelling suggests the C(5) and C(6) on the benzoquinone ring of the inhibitor interact with the oxygen atoms of Tyr-115 and Ser-209 respectively.
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PMID:Modification of glutathione S-transferase 3-3 mutants with 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone. Identification of the C-terminal tryptic fragment as part of the H-site and evidence that 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone is not specific for cysteine labelling. 781 87

Induction of glutathione S-transferase (GST) Ya gene expression by a variety of chemical agents is mediated by a regulatory element composed of two adjacent AP-1-like binding sites and activated by the Fos/Jun heterodimeric complex (AP-1). We have previously shown that the induction of GST Ya gene expression and of AP-1 binding activity is regulated by intracellular glutathione (GSH) levels. To study the role of reactive oxygen species in the induction of AP-1 activity and GST Ya gene expression and their effect on intracellular GSH levels, we have exposed hepatoma cells to adriamycin and two synthetic quinones, Qcb and Qn, with different capacities to generate oxygen radicals. The kinetics of quinone-mediated generation of hydroxyl radicals were monitored in intact cells by a spin trapping technique and EPR spectral measurements. We find that quinones which can chelate Fe(III) ions, adriamycin and Qcb, are more effective in hydroxyl radical production than the nonchelating quinone Qn. Furthermore, we show that the induction of AP-1 binding activity and GST Ya gene expression by these quinones correlates with their oxygen radical production, adriamycin and Qcb being stronger inducers that Qn. The present study indicates that the AP-1-mediated induction of GST Ya gene expression is part of the response to oxidative stress. A transient increase by 2.5-fold in the intracellular GSH level was observed 30 min after exposure of cells to quinone and was followed by a rapid depletion of GSH. This increase in the GSH level represents an induction of GSH synthesis since it was blocked by buthionine sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of quinone-mediated generation of hydroxyl radicals in the induction of glutathione S-transferase gene expression. 781 27

The in vivo metabolite patterns of 2,5-difluoroaminobenzene and of its nitrobenzene analogue, 2,5-difluoronitrobenzene, were determined using 19F NMR analysis of urine samples. Results obtained demonstrate significant differences between the biotransformation patterns of these two analogues. For the aminobenzene, cytochrome P450 catalysed aromatic hydroxylation presents the main metabolic pathway. 2,5-Difluoronitrobenzene was predominantly metabolised through glutathione conjugation leading to excretion of 5-fluoro-2-(N-acetylcysteinyl)-nitrobenzene and fluoride anions, and, to a minor extent, through cytochrome P450 catalysed hydroxylation and nitroreduction. Pretreatment of the rats with various inducers of cytochrome P450 enzymes, known also to influence glutathione S-transferase enzyme patterns, followed by exposure to the 2,5-difluoroamino- or 2,5-difluoronitrobenzene, generally resulted in metabolite patterns that varied only to a small (< or = 12%) extent. Based on these results it was concluded that the biotransformation enzyme pattern is not the predominant factor in determining the metabolic route of these two model compounds. Additional in vitro microsomal and cytosolic incubations with 2,5-difluoroaminobenzene and 2,5-difluoronitrobenzene qualitatively confirmed the in vivo results. NADPH/oxygen supported microsomal cytochrome P450 catalysed hydroxylation was observed only for 2,5-difluoroaminobenzene whereas cytosolic GSH conjugation occurred only in incubations with 2,5-difluoronitrobenzene as the substrate. Outcomes from molecular orbital calculations provided a working hypothesis that can explain the difference in metabolic pathways of the nitro- and aminobenzene derivative on the basis of their chemical characteristics. This hypothesis states that the chances for a nitro- or aminobenzene derivative to enter either a cytochrome P450 or a glutathione conjugation pathway are determined by the relative energy levels of the frontier orbitals of the compounds. The aminobenzene derivative has relatively high energy molecular orbitals leading to an efficient reaction of its highest occupied molecular orbital (HOMO) with the singly occupied molecular orbital of the cytochrome P450 (FeO)3+ intermediate, but a low reactivity of its lowest unoccupied molecular orbital (LUMO) with the HOMO of glutathione. The nitrobenzene, on the other hand, has molecular orbitals of relatively low energy, explaining the efficient interaction, and, thus, reaction between its LUMO and the HOMO electrons of glutathione, but resulting in low reactivity with the SOMO electron of the cytochrome P450 (FeO)3+ reaction intermediate.
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PMID:Different metabolic pathways of 2,5-difluoronitrobenzene and 2,5-difluoroaminobenzene compared to molecular orbital substrate characteristics. 782 Aug 80


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