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:1.11.1.9 (glutathione peroxidase)
22,002 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The protective function of alpha-tocopherol, glutathione (GSH), and glutathione peroxidase (GSH-Px) from tert-butyl hydroperoxide (t-BuOOH)-induced hemolysis was studied with the erythrocytes from male Wistar rats fed selenium (Se)-adequate or -deficient diet for 3 months. By the preincubation with a water-soluble radical initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), at 10 mM for 6 h at 37 degrees C, alpha-tocopherol levels of the erythrocytes were decreased to 40% of the original level, that is, to the level insufficient for supporting the normal functions of the erythrocytes. With the Se-deficient cells, the hemolysis proceeded rapidly irrespective of the presence or absence of GSH in the incubation medium, and irrespective of the presence or absence of AAPH in the preincubation medium. Contrarily, GSH suppressed the hemolysis of Se-adequate cells which were preincubated with and without AAPH. These results are consistent with the notion that Se serves as the prime, important defense mechanism in the t-BuOOH-induced hemolysis through the activity of GSH-Px. Either alpha-tocopherol or GSH by itself, or both by themselves, may not play so significant a role as Se does in suppressing the hemolysis.
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PMID:tert-butyl hydroperoxide-induced hemolysis of alpha-tocopherol-decreased erythrocytes from selenium-deficient and selenium-adequate rats. 323 Apr 19

In rats given ethanol 20% (v/v) in drinking water the hepatic antioxidant enzymes, superoxide dismutase (SOD), catalase and glutathione peroxidase were assayed at the end of 4 and 10 months of ethanol consumption. Simultaneously hepatic lipid peroxidation was monitored. At 4 months SOD and catalase were unaffected, while glutathione peroxidase was decreased by 48%. By the end of 10 months SOD had declined by 16% and glutathione peroxidase activity increased by 49%, while catalase again remained stable. However, hepatic lipid peroxidation was not significantly affected throughout the study. The controversy in the literature over the conflicting results of hepatic lipid peroxidation in chronically ethanol-fed rats is discussed in the light of mode, dose, duration of ethanol consumption, nutritional status of the rat, and primacy of glutathione peroxidase.
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PMID:Antioxidant and free radical-scavenging enzymes in chronically ethanol-consuming rats: controversy over hepatic lipid peroxidation. 323 29

It is becoming increasingly clear that certain types of pulmonary injury may be closely related to oxidant-antioxidant imbalance in the lung, resulting from the production of reactive oxygen species within the lung during endogenous metabolism and xenobiotic insult. We have investigated the role of glutathione in pneumoprotection from such reactive species and, in particular, methods of manipulating the resident antioxidant capacity of lung glutathione. One such approach has been the use of the thiol-containing drug N-acetylcysteine. We have shown that N-acetylcysteine is able to both support intracellular glutathione biosynthesis and act as a 'scavenger' of reactive electrophilic species through the chemical reactivity of its thiol group. N-acetylcysteine reduces hydrogen peroxide to water, with the commensurate formation of N-acetylcysteine disulphide both when the peroxide was supplied directly or generated enzymatically. This basal reduction of hydrogen peroxide by N-acetylcysteine was greatly enhanced by the inclusion of catalytic amounts of the selenium-containing heterocycle, Ebselen, in the incubations. Thus, Ebselen mimics the activity of glutathione peroxidase but, unlike the enzyme, is able to use N-acetylcysteine as a co-substrate. Thus, the combination of N-acetylcysteine and Ebselen may provide a useful therapeutic tool in conditions of pulmonary toxicity associated with oxidant insult.
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PMID:Lung protection by thiol-containing antioxidants. 331 62

Four communities with water supplies having selenium concentrations of less than 3.1, 1.7, 189, and 496 micrograms/liter were selected for study. Samples of blood, urine, and tap water were obtained from participants in each community and analyzed for selenium content. Blood samples were also analyzed for glutathione peroxidase activity. Results showed an increase in selenium concentration in the urine as the water selenium increased. Selenium concentrations in blood did not reflect the increased selenium exposure. Glutathione peroxidase activity in whole blood decreased in highly exposed participants compared to those with low exposure. We conclude that glutathione peroxidase activity in cases of possible environmental toxic exposures will not show the increased activity seen in supplementation of selenium to deficient subjects.
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PMID:Human glutathione peroxidase activity in cases of high selenium exposures. 333 32

Selenium-dependent glutathione peroxidase activity was assessed in the liver, kidney, lung and blood of mice from seven strains (129/ReJ, BALB/c, C3H/HeSnJ, C3H/S, C57BL/6J, Csb, and S.W.) at five ages (newborn, 21, 70, 175 and +500 days old). Activity was highest in the liver (0.25 U/mg protein) followed by blood hemolysate (0.16 U/mg protein) with kidney and lung displaying similar, comparatively lower levels of activity (0.14 and 0.12 U/mg protein respectively). Although activity was shown by statistical analysis to be not significantly different among the strains (p = 0.05), age-associated, strain-specific changes in enzyme activity were noted to be highly significant (p = 0.001). Also, ethanol administered in drinking water resulted in a marked reduction in selenium-dependent glutathione peroxidase activity during both short- (1-2 weeks) and long- (5-6 weeks) term treatment periods. Changes in this enzyme due to aging and after exposure to xenobiotics such as ethanol may have serious ramifications given the importance of this enzyme in the detoxification of reactive oxygen metabolites.
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PMID:Modulation of selenium-dependent glutathione peroxidase (Se-GSH-Px) activity in mice. 335 54

To evaluate nutritional availability and chronic toxicity of KSeCN, female postweanling rats were fed casein-based diets plus 0.1, 0.5, 2.5, 5 and 10 mg Se/kg as KSeCN for 6 wk, or 0.1, 0.5 and 10 mg Se/kg as Na2SeO3. A control group was fed the basal diet (Se = 0.04 mg/kg) and one group was fed the basal diet plus 5 mg Se/L as KSeCN in the drinking water. There were no differences in weight gain and diet consumption among groups fed 2.5 mg Se/kg or less. At 5 and 10 mg Se/kg, rats showed depression in weight gain and diet consumption. After wk 6 there were no abnormalities of the major organs of rats fed 2.5 mg Se/kg or less. Spleen enlargement was observed at 5 and 10 mg Se/kg, and liver damage and kidney enlargement at 10 mg Se/kg. Se content in the blood, liver and kidney of rats fed KSeCN was generally somewhat lower than for those fed Na2SeO3 at the same levels. The availability of Se from KSeCN for glutathione peroxidase formation in blood, liver and kidney was comparable to that of Na2SeO3. Plasma thyroxine in groups fed 10 mg Se/kg was 40% of that in the control group, but was not altered at lower Se levels.
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PMID:Nutritional availability and chronic toxicity of selenocyanate in the rat. 337 36

Severe gross and microscopic lesions and other changes were found in adult aquatic birds and in embryos from Kesterson Reservoir (a portion of Kesterson National Wildlife Refuge), Merced County, Calif., during 1984. Adult birds from that area were emaciated, had subacute to extensive chronic hepatic lesions, and had excess fluid and fibrin in the peritoneal cavity. Biochemical changes in their livers included elevated glycogen and non-protein-bound sulfhydryl concentrations and glutathione peroxidase activity but lowered protein, total sulfhydryl, and protein-bound sulfhydryl concentrations. Congenital malformations observed grossly in embryos were often multiple and included anophthalmia, microphthalmia, abnormal beaks, amelia, micromelia, ectrodactyly, and hydrocephaly. Mean concentrations of selenium in livers (94.4 ppm, dry weight) and kidneys (96.6 ppm) of birds collected at the Kesterson ponds were about 10 times those found at a nearby control area (8.3 and 12.2 ppm). We conclude that selenium present in the agricultural drainage water supplied to the Kesterson ponds accumulated in the food chain of aquatic birds to toxic concentrations and caused the lesion and other changes observed.
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PMID:Selenium toxicosis in wild aquatic birds. 337 65

This study aimed to elucidate the way in which larvae of the lamprey Geotria australis counteract the potential problems of the very high concentrations of non-haem iron they contain and thereby avoid the deleterious effects associated with iron overload in other vertebrates. Particular attention has been paid to ascertaining whether increasing concentrations of iron are accompanied by (i) change to a less readily available form of iron and (ii) an increase in the activity of those detoxifying enzymes responsible for minimizing the production of harmful hydroxyl radicals via the Haber-Weiss reaction. The mean concentrations of haemosiderin and ferritin in larval G. australis were each far higher in the nephric fold than in either the liver or intestine, but all these concentrations were much greater than those in rat liver. Since haemosiderin releases iron far more slowly than ferritin, the iron it contains is much less readily available to catalyse the Haber-Weiss reaction. It is thus relevant that (i) non-haem iron in the nephric fold occurred to a greater extent as large dense haemosiderin granules than as ferritin molecules and (ii) the proportion of iron in the form of haemosiderin rose with increasing concentration of total non-haem iron. A strong correlation was also recorded between the activity of superoxide dismutase in the nephric fold and the concentrations of total non-haem iron and its haemosiderin and ferritin components. This demonstrates that enzyme detoxification of O2.- rises with increasing amounts of iron. The exceptional iron concentrations in the nephric fold were not reflected by a greater measured activity of superoxide dismutase than that found in other tissues. However, the nephric fold was shown to contain an augmentation factor which is presumed to enhance the activity of this enzyme in vivo. The activity of catalase and glutathione peroxidase, which catalyse the breakdown of H2O2 to O2 and water, were each significantly correlated with the concentration of ferritin.
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PMID:Exceptional iron concentrations in larval lampreys (Geotria australis) and the activities of superoxide radical detoxifying enzymes. 342 99

The developmental profiles of the antioxidative defense system and the peroxidative status of the heart during growth and development were studied in pigs of three different age groups. A unique age-specific myocardial lipid peroxidation expressed in terms of malonaldehyde formation occurred after incubation of neonatal and adult pig heart homogenates in the absence of any added factors. Very little malonaldehyde release was noticed in the 0- to 2-day age group, while considerably higher activity was found in the 8- to 10-day-old animals. The 2-month-old pig heart again formed very little malonaldehyde. Myocardial injury from lipid peroxidation was highest in the 0- to 2-day age group, as evidenced by the release of oxidized glutathione, lactate dehydrogenase (LDH) and creatine kinase (CK) activities. Release of glutathione, LDH and CK decreased with age and was minimal in the adult group. The antioxidative enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, increased during the first 10 days of neonatal growth and then levelled off. Glucose-6-phosphate dehydrogenase was present in appreciably lower amounts in adult hearts compared to neonatal hearts. Heart weight increased with aging, but myocardial water content decreased. Protein and DNA contents of hearts increased with age, such that the protein/DNA ratio almost doubled from the newborn to adult age. The results indicate that the newborn pig hearts are equipped with the antioxidative defense system, which undergoes significant development during the initial phase of neonatal growth and does not change appreciably thereafter. The results further suggest that the change in activity profile with aging is different for different enzymes, and the peroxidative status of the myocardium is not a function of these enzyme activities.
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PMID:Age-related development profiles of the antioxidative defense system and the peroxidative status of the pig heart. 356 55

The effect of (1-benzoyl-1H-indazol-3-yl)oxylacetate L-Lysine (bendazac-lysine) on some enzymatic activities involved in the metabolism of reduced glutathione (GSH) was studied in the rabbit lens during developing cataract induced by a single dose of X-rays (2000 rads). The specific activities of glutathione reductase (G.R.), glutathione peroxidase (GSH.Px) and glutathione S-transferase (GSHS-tr.) do not change following irradiation and treatment with bendazac-lysine. The activity of the same enzymes expressed as a function of water soluble proteins (WSP) per lens significantly decreases (P less than 0.01) as compared to controls in the irradiated lens not treated with bendazac-lysine (ILNTB) at the 8th week, whereas no significant decrease as compared to controls is observed in the irradiated lens treated with bendazac-lysine (ILTB). In the ILNTB the specific activity of glucose-6-phosphate dehydrogenase (G6PDH) is reduced by 10% after 0.3 weeks and by 29% after 12 weeks. In the ILTB the specific activity of G6PDH is reduced by 8% after 0.3 weeks and by 14.5% after 12 weeks. The specific activity of superoxide dismutase (SOD) in the ILNTB is reduced by 19% after 0.3 weeks and reached 31% after 12 weeks. In the ILTB the specific activity of SOD is reduced by 11% after 0.3 weeks and 19.8% after 12 weeks. The mechanism of protective effect of bendazac-lysine on cataract is discussed.
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PMID:Effects of bendazac L-lysine salt on some metabolic enzymes of glutathione in the rabbit lens after X-irradiation. 361 May 98


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