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)

Levels of glutathione, glutathione reductase and glutathione S-transferase activities in rat lung and liver have been investigated. After perfusing the lung to remove contaminating blood, this organ was found to have an apparent concentration of glutathione (2mM) which is approx. 20% of that found in the liver. Both organs contain very low levels of glutathione disulfide. Neither phenobarbital nor methylcholanthrene had a significant effect on the levels of reduced glutathione in lung and liver. In addition, the activities of some glutathione-metabolizing enzymes--glutathione reductase and glutathione S-transferase activity assayed with four different substrates--were observed to be 5-to 60-fold lower in lung tissue than in the liver.
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PMID:Levels of glutathione, glutathione reductase and glutathione S-transferase activities in rat lung and liver. 76 Aug 19

Knowledge of the error structure of a given set of experimental data is a necessary prerequisite for incisive analysis and for discrimination between alternative mathematical models of the data set. A reaction system consisting of glutathione S-transferase A (glutathione S-aryltransferase), glutathione, and 3,4-dichloro-1-nitrobenzene was investigated under steady-state conditions. It was found that the experimental error increased with initial velocity, v, and that the variance (estimated by replicates) could be described by a polynomial in v Var (v) = K0 + K1 - v + K2 - v2 or by a power function Var (v) = K0 + K1 - vK2. These equations were good approximations irrespective of whether different v values were generated by changing substrate or enzyme concentrations. The selection of these models was based mainly on experiments involving varying enzyme concentration, which, unlike v, is not considered a stochastic variable. Different models of the variance, expressed as functions of enzyme concentration, were examined by regression analysis, and the models could then be transformed to functions in which velocity is substituted for enzyme concentration owing to the proportionality between these variables. Thus, neither the absolute nor the relative error was independent of velocity, a result previously obtained for glutathione reductase in this laboratory [BioSystems 7, 101-119 (1975)]. If the experimental errors or velocities were standardized by division with their corresponding mean velocity value they showed a normal (Gaussian) distribution provided that the coefficient of variation was approximately constant for the data considered. Furthermore, it was established that the errors in the independent variables (enzyme and substrate concentrations) were small in comparison with the error in the velocity determinations. For weighting in regression analysis the inverted value of the local variance in each experimental point should be used. It was found that the assumption of proportionality between variance and valpha (where alpha is an empirically determined exponent) was a good approximation for the weighting. The value of alpha was 1.6 in the present case. The weight function was tested in the fitting of a rate equation to a kinetic-data set involving variable substrate concentrations. Recommendations are given regarding the establishment of the error structure in a general case and its application in regression analysis.
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PMID:Error structure of enzyme kinetic experiments. Implications for weighting in regression analysis of experimental data. 99 63

Studies on glutathione metabolism in an established baby hamster kidney cell line (BHK-21/C13) and in its polyoma virus-transformed counterpart (BHK-21/PyY), have revealed a significant stimulation of intracellular glutathione peroxidase activity (Se-independent plus Se-dependent) by alpha-tocopherol supplementation (14 microM). This stimulation was found to be much greater in the transformed cells. Other GSH-requiring enzyme activities (namely glutathione reductase and glutathione transferase) were unaltered by alpha-tocopherol treatment, suggesting a degree of specificity in its action on GSHpx. In unsupplemented growth media, the GSHpx activity in both cell lines was significantly decreased by an oxidative stress. However, the same stress applied to the alpha-tocopherol-supplemented cells had no effect on the stimulated GSHpx activity, suggesting a protection afforded by the alpha-tocopherol.
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PMID:Variable alpha-tocopherol stimulation and protection of glutathione peroxidase activity in non-transformed and transformed fibroblasts. 133 9

The present study examines the effect of butylated hydroxyanisole (BHA) exposure through mother's milk on some of the hepatic xenobiotic metabolizing enzymes in the F1 offspring. Lactating Swiss albino mice received either a 0.5 or 1% BHA diet during the lactation period. The acid-soluble sulfhydryl content and activities of glutathione S-transferase and glutathione reductase increased significantly (p < 0.01) whereas the activity of glutathione peroxidase decreased significantly (p < 0.01) in the liver of pups exposed to BHA via milk. The hepatic content of cytochrome b5 increased (p < 0.01) while that of cytochrome P-450 decreased (p < 0.01) in the pups of dams which received a 1% BHA diet during lactation.
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PMID:Neonatal modulation of hepatic acid soluble sulfhydryls and xenobiotic metabolizing enzymes in suckling mice exposed translactationally to butylated hydroxyanisole. 134 Apr 32

Female beagle dogs were treadmill trained 40 km/day at 5.5-6.8 km/h, 15% upgrade, 5 days/wk for 55 wk. With training, hepatic and red gastrocnemius (RG) total glutathione increased, glutathione peroxidase (GPX) and glutathione reductase (GRD) increased in all the leg muscles studied, and hepatic glutathione S-transferase (GST) activity increased. Joint immobilization (11 wk) did not affect GPX, GRD, and GST of RG, but total glutathione decreased. Male Han Wistar rats were treadmill trained 2 h/day at 2.1 km/h, 5 days/wk for 8 wk. With training, hepatic total glutathione and leg muscle GPX increased but GRD of RG decreased, perhaps because of an increased muscle flavo-protein breakdown during exhaustive training. gamma-Glutamyl transpeptidase was higher in the trained leg muscles. Exhaustive exercise decreased muscle gamma-glutamyl transpeptidase of only control leg muscle, depleted muscle (lesser extent in trained rats) and liver total glutathione of both groups, decreased GRD only in untrained RG, and increased hepatic GST. Endurance training elevated the antioxidant and detoxicant status of muscle and liver, respectively.
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PMID:Skeletal muscle and liver glutathione homeostasis in response to training, exercise, and immobilization. 136 1

1. Six enzymes which collectively catalyze a number of glutathione-dependent synthetic, catabolic and detoxification reactions were examined along with glutathione status in liver, gills, and posterior kidney of channel catfish (Ictalurus punctatus). 2. Hepatic GSH concentrations were higher than those in kidney or gills. Oxidized glutathione (GSSG) concentrations were similar among the three tissues. 3. Specific (per unit protein) gamma-glutamylcysteine synthetase (GCS) activity was greater in the gills than in liver or posterior kidney. However, total organ GCS activity was greatest in the liver. 4. Specific and total hepatic glutathione peroxidase (GSH peroxidase) activities were substantially greater than those of gills or kidney. 5. Similar specific glutathione reductase (GSSG reductase) activities were observed among all three tissues. 6. All three tissues exhibited glutathione S-transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene (CDNB). Specific and total organ GST activities were highest in the liver, followed by the posterior kidney and gills. 7. Gamma-glutamyltranspeptidase (GGT) activity was present in the posterior kidney, but was undetectable in the gills or liver.
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PMID:A comparison of glutathione-dependent enzymes in liver, gills and posterior kidney of channel catfish (Ictalurus punctatus). 136 Mar 60

A disruption of calcium homeostasis, leading to a sustained increase in cytosolic calcium levels, has been associated with cytotoxicity in response to a variety of agents in different cell types. We have observed that administration of a single high dose or multiple lower doses of the carcinogenic nephrotoxin ochratoxin A (OTA) to rats resulted in an increase of the renal cortex endoplasmic reticulum ATP-dependent calcium pump activity. The increase was very rapid, being evident within 10 min of OTA administration and remained elevated for at least 6 hr thereafter. The increase in calcium pump activity was inconsistent with previous observations that OTA enhances lipid peroxidation (ethane exhalation) in vivo, a condition known to inhibit the calcium pump. However, no evidence of enhanced lipid peroxidation was observed in the renal cortex since levels of malondialdehyde and a variety of antioxidant enzymes including catalase, DT-diaphorase, superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione S-transferase were either unaltered or reduced. In in vitro studies, addition of OTA to cortex microsomes during calcium uptake inhibited the uptake process although the effect was reversible. Preincubation of microsomes with NADPH had a profound inhibitory effect on calcium uptake but inclusion of OTA was able to reverse the inhibition. Changes in the rates of microsomal calcium uptake correlated with changes in the steady-state levels of the phosphorylated Mg2+/Ca(2+)-ATPase intermediate, suggesting that in vivo/in vitro conditions were affecting the rate of enzyme phosphorylation.
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PMID:Alterations in ATP-dependent calcium uptake by rat renal cortex microsomes following ochratoxin A administration in vivo or addition in vitro. 141 61

The authors investigated the content of reduced glutathione, activity of glutathione peroxidase, glutathione transferase, glutathione reductase, glucoso-6-phosphate dehydrogenase in the liver tissue, gastric mucosa of rats with experimental ulcer and in the blood of patients with gastric and duodenal ulcer in the course of treatment using new protein tableted products. Experimental investigations were conducted on 96 white rats, clinical studies in 128 patients and 59 healthy persons. It was shown that high therapeutic efficiency of these new tableted products, their normalizing effects on the glutathione system indices are important.
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PMID:[New tableted protein products in the treatment of peptic ulcer patients and the dynamic indices of the glutathione system]. 144 29

Circadian variations in antioxidant defences and lipid peroxidation were investigated in 12 rat hearts perfused during light (i.e., at 08.00, n = 6) and dark cycle (i.e., at 19.00, n = 6). Higher levels of non proteic thiol compounds (P < 0.01), glutathione transferase activity (P < 0.05) and lipid peroxidation (P < 0.01) were detected in evening-excised hearts, associated with a lower (P < 0.05) selenium-dependent glutathione peroxidase activity; superoxide dismutase and glutathione reductase activities, as well as vitamin E content, were similar in the two groups. Moreover, a greater release of thiobarbituric acid reactive substances (P < 0.01) and proteins (P < 0.05) was detected in the myocardial effluent of another group of 5 evening-excised hearts perfused with Krebs-Henseleit buffer containing 30 microM cumene hydroperoxide, as compared to 5 light-cycle hearts. In conclusion, a higher oxidative stress seems to be operative in the rat heart during early stages of the dark phase, in spite of the increase level of non proteic thiol compounds (namely, glutathione). An imbalance of antioxidant defences, and/or higher radical generation and unsaturation degree of biomembranes lipids, may be hypothesized to favour myocardial oxidative stress at the beginning of the motor activity phase in rats.
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PMID:Circadian variations in antioxidant defences and lipid peroxidation in the rat heart. 145 91

In 7 rabbits fed on hyperlipidic diet (0.5% cholesterol, 5% peanut oil and 5% lard) for 4 weeks, the ventricular myocardium was tested for antioxidant defences and thiobarbituric acid reactive substances. Seven age-matched rabbits served as controls. The hearts were previously subjected to 45 min Langendorff perfusion to study coronary flow, developed tension and resting tension; coronary effluent values of CPK activity, pH and UV absorbance at 250 nm (i.e., low molecular weight ATP catabolites) were also investigated. After 4 weeks of diet, a significant rise of plasma cholesterol (P < 0.0001) and triglycerides (P < 0.0001) was observed. Total superoxide dismutase, catalase and glutathione transferase activities underwent a significant increase (P < 0.05) in the hyperlipidemic animals. On the contrary, a depression of glutathione reductase (P < 0.01) and selenium-dependent glutathione peroxidase (P < 0.01) activities, associated with decreased levels of non proteic thiol compounds (P < 0.01), was assessed. The selenium-independent glutathione peroxidase activity was not detectable in both groups. Thiobarbituric acid reactive substances levels were significantly increased in the hyperlipidemic rabbit myocardium (P < 0.01). Even though heart hemodynamics, CPK release and perfusate pH did not differ in control and experimental animals, higher 250 nm absorbance values (P < 0.05) were detected in the myocardial effluent of hyperlipidemic rabbits. In conclusion, high fat-, cholesterol-enriched diet induces an imbalance in the rabbit heart antioxidant defences, some of which are increased, whereas others are depressed, eventually resulting in enhanced myocardial lipid peroxidation. These biochemical changes are associated with higher perfusate values of UV absorbance at 250 nm, but not with significant CPK leakage or myocardial hemodynamics derangement.
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PMID:Effects of high fat-, cholesterol-enriched diet on the antioxidant defence mechanisms in the rabbit heart. 146 87


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