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)

A purification scheme is described for a glutathione S-transferase (GST) from human liver that catalyses the conjugation of 1-menaphthyl sulphate (MS) with GSH; the method devised results in an approx. 500-fold increase in specific activity towards MS. The human enzyme which metabolizes MS is a homodimer comprising subunits of M(r) 25,100, and immunochemical experiments have shown it to be a member of the class-Theta GSTs. Automated Edman degradation of this enzyme has confirmed that it is a Theta-class GST bu the amino acid sequence obtained differs from that of GST theta described previously [Meyer, Coles, Pemble, Gilmore, Fraser & Ketterer (1991) Biochem. J. 274, 409-414]. We have therefore designated the enzyme that catalyses the conjugation of MS with GSH GST T2-2* (in the absence of complete amino acid sequence data, the T1 and T2 subunits are provisionally designated T1* and T2*); the evidence which indicates that GST theta (which should possibly now be called GST T1-1*) and GST T2-2* represent distinct isoenzymes is discussed.
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PMID:Characterization of a human class-Theta glutathione S-transferase with activity towards 1-menaphthyl sulphate. 141 52

Influences of dietary selenium (Se) deficiency, physical training and an acute bout of exercise on myocardial antioxidant enzyme activity, lipid peroxidation and related biochemical properties were investigated in post-weanling male Sprague-Dawley rats. An experimental group was fed a diet containing less than 0.01 mg Se/kg and had free access to distilled water (Se-D), whereas control rats were supplemented with 0.5 mg Se/l in drinking water (Se-A). Se deficiency depleted heart mitochondrial and cytosolic Se-dependent glutathione peroxidase activity to 24 and 3%, respectively, of those in Se-A rats. Heart mitochondrial superoxide dismutase (Mn SOD) activity was 24% higher (p less than 0.05) in Se-D than in Se-A rats. Cytosolic (copper-zinc) SOD and catalase activities were not altered, whereas glutathione S-transferase activity was significantly decreased in Se-D (p less than 0.01). Myocardial antioxidant enzyme activities were not affected by either training or an acute exercise bout. Heart lipid peroxidation and activities of several enzymes in substrate metabolism were also unaffected by Se or exercise. It is concluded that rat heart has sufficient reserve of antioxidant enzyme capacity in coping with oxidative stress imposed by Se deficiency or exercise. The adaptation of Mn SOD may reveal its potential role in myocardial antioxidant defense.
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PMID:Antioxidant enzyme response to selenium deficiency in rat myocardium. 153 41

A novel class alpha glutathione S-transferase (GST) isozyme is expressed in the hepatic cytosol of rabbits treated with 4-picoline. SDS-PAGE analysis revealed the presence of a new 28-kDa band which cross-reacted with class alpha GST-specific IgG. This new GST isozyme was isolated from the hepatic cytosol of 4-picoline-treated rabbits and purified to homogeneity using S-hexylglutathione-agarose, CM-Sepharose, and PBE118 chromatofocusing chromatography. The isozyme was determined by SDS-PAGE and gel filtration analyses to be a homodimer of approximately 28 kDa with blocked N-terminus. A heterodimer consisting of 25 and 28 kDa subunits with activity toward the substrate 1-chloro-2,4-dinitrobenzene was also purified. Immunoblot analysis revealed that the 25, 26.5, and 28 kDa bands cross-reacted with class alpha GST-specific IgG and failed to react with either class mu or class pi GST-specific antibodies. The 28 kDa enzyme had a pI of 8.2 as determined by nonequilibrium pH gel electrophoresis. The purified 28 kDa enzyme exhibited activity toward 1-chloro-2,4-dinitrobenzene (Km = 1.60 mM and Vmax = 73.5 mumol/min/mg) and cumene hydroperoxide (Km = 1.02 mM and Vmax = 6.92 mumol/min/mg). Amino acid sequence analysis of several fragments resulting from cyanogen bromide cleavage of the 28 kDa GST isozyme revealed a class alpha GST consensus sequence. In addition, proteolytic digestion with alpha-chymotrypsin yielded peptide maps which showed distinct differences between the purified 28 kDa GST and another purified class alpha GST isozyme present in rabbit liver. These results provide evidence that class alpha GST isozymes containing a novel 28 kDa subunit are expressed following treatment with 4-picoline.
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PMID:Enhanced expression, purification, and characterization of a novel class alpha glutathione S-transferase isozyme appearing in rabbit hepatic cytosol following treatment with 4-picoline. 153 65

1. The activity of antioxidant defense enzymes (SOD, CAT, GSH-Px and GST) was analysed during the autumn and winter in the ground squirrel adapted to 30 degrees C and subsequently exposed to cold for 6 and 24 hr. 2. The liver CAT activity as well as the IBAT CAT and GSH-Px activities differed between animals adapted to 30 degrees C, studied in autumn, and those studied in winter. 3. MnSOD activity in the liver was increased in autumn but decreased in winter after 6 hr cold exposure reaching the control level 24 hr later. Cold exposure induced a decrease in CAT activity (except after 24 hr cold exposure in winter) and an increase in GSH-Px activity. Lower GST activity was found after 24 hr exposure to cold in winter. 4. The IBAT SOD activity decreased under the influence of cold during both seasons with a tendency to return to the control level only in winter. Cold exposure produced a decrease in GST in both seasons and CAT activity in autumn. GSH-Px activity was increased in winter only. 5. The results indicate a seasonal dependence of the activity of antioxidant defence enzymes in the ground squirrel. Seasonal influence was evidenced in animals exposed to cold as well.
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PMID:Seasonal dependence of the activity of antioxidant defence enzymes in the ground squirrel (Citellus citellus): the effect of cold. 161 72

HA-1 hamster fibroblasts receiving fresh media every 24 h were continuously passaged in progressively increasing O2 concentrations for 18 mo (designated O2R95). These cells were significantly more resistant than parental HA-1 to clonogenic inactivation mediated by 95% O2 without media replacement. The O2R95 cell line exhibited increases in the activities of catalase (CAT), Mn superoxide dismutase (MnSOD), Cu,Zn superoxide dismutase (Cu,Zn SOD), and glutathione peroxidase (GPx). O2R95 cells demonstrated uniformly distributed increased staining for CAT, MnSOD, Cu,Zn SOD, and GPx proteins, as determined by immunohistochemistry. Cellular resistance to and metabolism of 4-hydroxy-2-nonenal (4HNE), a toxic byproduct of lipid peroxidation implicated in mechanisms of O2 toxicity, was examined in HA-1 and O2R95 cell lines. O2R95 cells were significantly more resistant to 4HNE cytotoxicity, which was accompanied by a significant increase in 4HNE metabolism. O2R95 cells also demonstrated an increase in total glutathione (GSH) and glutathione S-transferase (GST) activity, an enzymatic system believed to be involved with 4HNE metabolism. Furthermore, homogenates from O2R95 cells consumed greater quantities of 4HNE in the presence of NADPH (but not NADH, NAD+, or NADP+), suggesting that an enzyme(s) utilizing NADPH contributes to 4HNE metabolism, resistance to 95% O2 and 4HNE as well as increased total GSH, antioxidant enzyme activities, and NADPH-dependent metabolism of 4HNE, persisted in O2R95 cells for 75 days of growth in 21% O2. These findings are compatible with the hypothesis that aldehydic byproducts of lipid peroxidation contribute to mechanisms of O2 toxicity and the selective pressure exerted by exposure of cells to hyperoxia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A stable O2-resistant cell line: role of lipid peroxidation byproducts in O2-mediated injury. 161 58

The rat cytosolic glutathione S-transferase Ya subunit contains three histidine residues (at positions 8, 143, and 159), two cysteine residues (at positions 18 and 112), and a single tryptophan residue (at position 21). Histidine, cysteine, and tryptophan have been proposed to be present either near or at the active site of other glutathione S-transferase subunits. The functional role of these amino acids at each of the positions was evaluated by site-directed mutagenesis in which valine or asparagine, alanine, and phenylalanine were substituted for histidine, cysteine, and tryptophan, respectively. Mutant enzymes H8V, H143V, H159N, C112A, and W21F retained either full or better catalytic efficiencies (k(cat)/Km) toward 1-chloro-2,4-dinitrobenzene and glutathione. Lower but significant k(cat)/Km values were observed for H159V and C18A toward 1-chloro-2,4-dinitrobenzene. Some mutants displayed different thermal stabilities and intrinsic fluorescence intensities, but all retained the ability to bind heme. These results indicate that histidine, cysteine, and tryptophan in the glutathione S-transferase Ya subunit are not essential for catalysis nor are they involved in the binding of heme to the YaYa homodimer.
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PMID:Site-directed mutagenesis of glutathione S-transferase YaYa: functional studies of histidine, cysteine, and tryptophan mutants. 163 85

1. The major glutathione S-transferase (GST) from the common squid Loligo vulgaris has been purified and shown to be a homodimer of subunit molecular mass 24,000 and pI 6.8. 2. It has high activity towards 1-chloro-2,4-dinitrobenzene, p-nitrobenzyl chloride, 4-hydroxynon-2-enal and linoleic acid hydroperoxide, low activity with 1,2-dichloro-4-nitrobenzene and no activity with ethacrynic acid, trans-4-phenyl-3-buten-2-one and 1,2-epoxy-3-(p-nitrophenoxy)propane. 3. The L. vulgaris GST did not cross-react with any of the available polyclonal antibodies raised against mammalian GSTs. 4. Forty amino acids of its N-terminal sequence have been determined. 5. Its activities and primary structure are compared with related proteins from other species.
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PMID:The isolation and characterization of the major glutathione S-transferase from the squid Loligo vulgaris. 186 85

A cDNA encoding a rat liver glutathione S-transferase Ya subunit has been expressed in Escherichia coli and the expressed enzyme purified to homogeneity. In order to examine the catalytic role of histidine in the glutathione S-transferase Ya homodimer, site-directed mutagenesis was used to replace all three histidine residues (at positions 8, 143, and 159) by other amino acid residues. The replacement of histidine 8 or histidine 143 with valine did not affect the 1-chloro-2,4-dinitrobenzene-conjugating activity nor the isomerase activity. However, the replacement of histidine with valine at position 159 produced the mutant GST which exhibited only partial activity. A greater decrease in catalytic activity was observed by histidine----tyrosine or histidine----lysine replacement at position 159. On the other hand, the histidine 159----asparagine mutant retained full catalytic activity. Our results indicate that histidine residues in the Ya homodimer are not essential for catalytic activity. However, histidine 159 might be critical in maintaining the proper conformation of this enzyme since replacement of this amino acid by either lysine or tyrosine did result in significant loss of enzymatic activity.
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PMID:Site-directed mutagenesis of glutathione S-transferase YaYa: nonessential role of histidine in catalysis. 189 79

The level of quinone oxidoreductases (microsomal and cytosolic DT-diaphorase, NADPH-cytochrome P450 reductase and NADH-cytochrome b5 reductase), superoxide dismutase and glutathione-related enzymatic activities in diethylstilbestrol (DES)-induced carcinogenesis in kidney from Syrian golden hamsters are presented. Animals that exhibited two different stages of DES-induced carcinogenesis in kidney--pre- and neoplastic lesions and tumorous lesions (after 6 and 8 months of continuous exposure to DES respectively)--were studied in comparison to kidneys from control animals. A dramatic decrease in microsomal and cytosolic DT-diaphorase activities (13.6 and 37.8% of controls), as well as in glutathione disulphide reductase (39.5%), and less marked in superoxide dismutase (45.6%), NADH cytochrome b5 reductase (61.9%) glutathione transferase (GST) towards 1-chloro-2,4-dinitrobenzene (CDNB) (66.2%) and glutathione peroxidase (GSH-Px) (80%) activities, were observed in kidneys with pre- and neoplastic lesions. NADPH-cytochrome P450 reductase and GST activity towards 4-hydroxy-2,3-trans-nonenal (4-HNE) showed no statistically significant variation at this stage of carcinogenesis. In kidney from animals with tumorous lesions, all the enzymatic activities mentioned above decreased, except for superoxide dismutase, which was increased to 186% of the control activity. GST activity towards 4-HNE again showed no statistically significant variation. These results suggest that if one-electron reduction of diethylstilbestrol-4',4''-quinone (DESQ) occurs, it may play a very important role in the development of DES carcinogenesis (pre- and neoplastic lesions), since at this stage of carcinogenesis the primary defense mechanisms against the oxygen free radicals generated in this way, i.e. SOD activity, is reduced to less than a half of control values. Both cytosolic and microsomal DT-diaphorase activities are unable at this stage of carcinogenesis to promote effectively the two-electron reduction of DESQ, which would avoid the initial formation of superoxide anion. The consequences of these decreases may be an increased steady-state concentration of superoxide anion and hydrogen peroxide, which in the presence of iron might lead to lipid peroxidation. GST activity towards 4-HNE could be responsible for the possible higher steady-state concentration of this lipid peroxidation product during DES treatment. The induction of DT-diaphorase and its protective role in the prevention of the development of pre- and neoplastic lesions in kidney from Syrian golden hamster during DES treatment is also discussed.
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PMID:The levels of quinone reductases, superoxide dismutase and glutathione-related enzymatic activities in diethylstilbestrol-induced carcinogenesis in the kidney of male Syrian golden hamsters. 211 5

A glutathione S-transferase from Escherichia coli has been purified approximately 800-fold with an 11% activity yield by passage through DEAE Sephacel and glutathione-agarose affinity columns. Its functional form is a homodimer of two 24,000 Da polypeptides that catalyzes the binding of glutathione and 1-chloro-2,4-dinitrobenzene with Km values of 0.25 and 1.5 mM, respectively. Optima of pH and temperature were 7.5 and 35 degrees C. The activity was stimulated (30%) by ethylenediaminetetraacetic acid. The N-terminal amino acid sequence was: Met-Leu-Leu-Phe-Ile-Leu-Pro-Gly-Ala.
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PMID:Purification and study of a bacterial glutathione S-transferase. 218 38


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