Showing papers on "Glutathione published in 1992"
TL;DR: Results suggest that the demonstrated preferential transport of GSSG compared to GSH into the ER lumen may contribute to this redox compartmentation.
Abstract: The redox state of the endoplasmic reticulum (ER) was measured with the peptide N-Acetyl-Asn-Tyr-Thr-Cys-NH2. The peptide diffused across cellular membranes; some became glycosylated and thus trapped within the secretory pathway, and its cysteine residue underwent reversible thiol-disulfide exchanges with the surrounding redox buffer. Glycosylated peptides from cells were disulfide-linked to glutathione, indicating that glutathione is the major redox buffer in the secretory pathway. The redox state of the secretory pathway was more oxidative than that of the cytosol; the ratio of reduced glutathione to the disulfide form (GSH/GSSG) within the secretory pathway ranged from 1:1 to 3:1, whereas the overall cellular GSH/GSSG ratio ranged from 30:1 to 100:1. Cytosolic glutathione was also transported into the lumen of microsomes in a cell-free system. Although how the ER maintains an oxidative environment is not known, these results suggest that the demonstrated preferential transport of GSSG compared to GSH into the ER lumen may contribute to this redox compartmentation.
1,831 citations
TL;DR: In this paper, exposure of human ovarian tumor cell lines to cisplatin led to development of cell lines that exhibited increasing degrees of drug resistance, which were closely correlated with increase of the levels of cellular glutathione.
Abstract: Exposure of human ovarian tumor cell lines to cisplatin led to development of cell lines that exhibited increasing degrees of drug resistance, which were closely correlated with increase of the levels of cellular glutathione. Cell lines were obtained that showed 30- to 1000-fold increases in resistance; these cells also had strikingly increased (13- to 50-fold) levels of glutathione as compared with the drug-sensitive cells of origin. These levels of resistance to cisplatin and the cellular glutathione levels are substantially greater than previously reported. Very high cisplatin resistance was associated with enhanced expression of mRNAs for gamma-glutamylcysteine synthetase and gamma-glutamyl transpeptidase; immunoblots showed increase of gamma-glutamylcysteine synthetase but not of glutathione synthetase. Glutathione S-transferase activity was unaffected, as determined with chlorodinitrobenzene as a substrate. These studies suggest the potential value of examining regulation of glutathione synthesis as an indicator of clinical prognosis. The highly resistant cell lines are proving useful for studying the multiple mechanisms by which tumor cells acquire drug- and radiation-resistance.
900 citations
TL;DR: Antioxidant functions are associated with lowering DNA damage, malignant transformation, and other parameters of cell damage in vitro as well as epidemiologically with lowered incidence of certain types of cancer and degenerative diseases, such as ischemic heart disease and cataract.
Abstract: Tocopherols and tocotrienols (vitamin E) and ascorbic acid (vitamin C) as well as the carotenoids react with free radicals, notably peroxyl radicals, and with singlet molecular oxygen (1O2), this being the basis of their function as antioxidants. RRR-alpha-tocopherol is the major peroxyl radical scavenger in biological lipid phases such as membranes or low-density lipoproteins (LDL). L-Ascorbate is present in aqueous compartments (e.g. cytosol, plasma, and other body fluids) and can reduce the tocopheroxyl radical; it also has a number of metabolically important cofactor functions in enzyme reactions, notably hydroxylations. Upon oxidation, these micronutrients need to be regenerated in the biological setting, hence the need for further coupling to nonradical reducing systems such as glutathione/glutathione disulfide, dihydrolipoate/lipoate, or NADPH/NADP+ and NADH/NAD+. Carotenoids, notably beta-carotene and lycopene as well as oxycarotenoids (e.g. zeaxanthin and lutein), exert antioxidant functions in lipid phases by free-radical or 1O2 quenching. There are pronounced differences in tissue carotenoid patterns, extending also to the distribution between the all-trans and various cis isomers of the respective carotenoids. Antioxidant functions are associated with lowering DNA damage, malignant transformation, and other parameters of cell damage in vitro as well as epidemiologically with lowered incidence of certain types of cancer and degenerative diseases, such as ischemic heart disease and cataract. They are of importance in the process of aging. Reactive oxygen species occur in tissues and cells and can damage DNA, proteins, carbohydrates, and lipids. These potentially deleterious reactions are controlled in part by antioxidants that eliminate prooxidants and scavenge free radicals. Their ability as antioxidants to quench radicals and 1O2 may explain some anticancer properties of the carotenoids independent of their provitamin A activity, but other functions may play a role as well. Tocopherols are the most abundant and efficient scavengers of peroxyl radicals in biological membranes. The water-soluble antioxidant vitamin C can reduce tocopheroxyl radicals directly or indirectly and thus support the antioxidant activity of vitamin E; such functions can be performed also by other appropriate reducing compounds such as glutathione (GSH) or dihydrolipoate. The biological efficacy of the antioxidants is also determined by their biokinetics.
800 citations
TL;DR: The ATP-dependent glutathione S-conjugate export pump (GS-X pump) plays a physiologically important role as a member of the 'phase III' system in xenobiotic metabolism as well as in the release of biologically active endogenous substances from cells.
640 citations
TL;DR: The finding that oxidized glutathione is not decreased in Parkinson's disease suggests that the decrease in reduced glutathion is not exclusively the consequence of neuronal loss in the substantia nigra but may indicate a state of oxidative stress.
583 citations
TL;DR: The assay is sufficiently sensitive to detect the various forms of the four thiol compounds in human plasma and the analytical recovery of cysteine, cysteinylglycine, homocysteines, and glutathione was close to 100%, and the within-day precision corresponded to a coefficient of variation of 7, 8, 6, and 7%, respectively.
521 citations
TL;DR: It is concluded that copper tolerance in S. cucubalus does not depend on the production of phytochelatins but is related to the plant's ability to prevent glutathione depletion resulting from copper-induced phytOChelatin production, e.g. by restricting its copper uptake.
Abstract: The relation between loss of glutathione due to metal-induced phytochelatin synthesis and oxidative stress was studied in the roots of copper-sensitive and tolerant Silene cucubalus (L.) Wib., resistant to 1 and 40 micromolar Cu, respectively. The amount of nonprotein sulfhydryl compounds other than glutathione was taken as a measure of phytochelatins. At a supply of 20 micromolar Cu, which is toxic for sensitive plants only, phytochelatin synthesis and loss of total glutathione were observed only in sensitive plants within 6 h of exposure. When the plants were exposed to a range of copper concentrations for 3 d, a marked production of phytochelatins in sensitive plants was already observed at 0.5 micromolar Cu, whereas the production in tolerant plants was negligible at 40 micromolar or lower. The highest production in tolerant plants was only 40% of that in sensitive plants. In both varieties, the synthesis of phytochelatins was coupled to a loss of glutathione. Copper at toxic concentrations caused oxidative stress, as was evidenced by both the accumulation of lipid peroxidation products and a shift in the glutathione redox couple to a more oxidized state. Depletion of glutathione by pretreatment with buthionine sulfoximine significantly increased the oxidative damage by copper. At a comparably low glutathione level, cadmium had no effect on either lipid peroxidation or the glutathione redox couple in buthionine sulfoximine-treated plants. These results indicate that copper may specifically cause oxidative stress by depletion of the antioxidant glutathione due to phytochelatin synthesis. We conclude that copper tolerance in S. cucubalus does not depend on the production of phytochelatins but is related to the plant9s ability to prevent glutathione depletion resulting from copper-induced phytochelatin production, e.g. by restricting its copper uptake.
480 citations
TL;DR: It is suggested that the interaction of MPP+ with complex I induces free radical generation, which in turn leads to the irreversible inhibition of complex I activity, which has important implications for the interpretation of the increased oxidative stress observed in Parkinson's disease substantia nigra.
Abstract: Incubation of 10 mM 1-methyl-4-phenylpyridinium (MPP+) with sonicated beef heart mitochondria caused an irreversible time-dependent decrease in NADH-ubiquinone-1 (CoQ1) reductase activity (52% inhibition after 1 h). Inclusion of glutathione, ascorbate, or catalase in the incubation mixture protected the NADH-CoQ1 reductase activity. These results suggest that the interaction of MPP+ with complex I induces free radical generation, which in turn leads to the irreversible inhibition of complex I activity. The generation of free radicals by neurotoxin-induced inhibition of complex I has important implications for our interpretation of the increased oxidative stress observed in Parkinson's disease substantia nigra and for our understanding of the cause(s) of dopaminergic cell death in this disorder.
389 citations
Journal Article•
TL;DR: Following the oral feeding of a polyphenolic fraction isolated from green tea (GTP) in drinking water, an increase in the activities of antioxidant and phase II enzymes in skin, small bowel, liver, and lung of female SKH-1 hairless mice was observed.
Abstract: Following the oral feeding of a polyphenolic fraction isolated from green tea (GTP) in drinking water, an increase in the activities of antioxidant and phase II enzymes in skin, small bowel, liver, and lung of female SKH-1 hairless mice was observed. GTP feeding (0.2%, w/v) to mice for 30 days significantly increased the activities of glutathione peroxidase, catalase, and quinone reductase in small bowel, liver, and lungs, and glutathione S-transferase in small bowel and liver. GTP feeding to mice also resulted in considerable enhancement of glutathione reductase activity in liver. In general, the increase in antioxidant and phase II enzyme activities was more pronounced in lung and small bowel as compared to liver and skin. The significance of these results can be implicated in relation to the cancer chemopreventive effects of GTP against the induction of tumors in various target organs.
325 citations
TL;DR: Assay conditions for Se-GPX and total GPX activities were determined which optimized the difference between the non-enzymic and enzymic rates of reaction, andCatalase properties were consistent with a catalase, rather than aCatalase-peroxidase, and the pH-dependence and temperature-dependency of GPX activity were different with H2O2 or CHP as substrate, and these and other observations indicate the existence of a distinct Se
Abstract: Antioxidant enzymes function to remove deleterious reactive oxygen species, including the superoxide anion radical and H2O2. Subcellular distributions and optimal and other properties of catalase (EC. 1.11.1.6), superoxide dismutase (SOD; EC. 1.15.1.1), selenium-dependent glutathione peroxidase (Se-GPX; EC. 1.11.1.9) and total glutathione peroxidase (GPX) activities were determined in the digestive gland of the common musselMytilus edulis L. by spectrophotometric and cytochemical/electron microscopic (catalase) techniques. Assay conditions for Se-GPX and total GPX activities were determined which optimized the difference between the non-enzymic and enzymic rates of reaction. General peroxidase activity (guaiacol as substrate) (EC. 1.11.1.7) was not detectable in any subcellular fraction. Catalase was largely, if not totally, peroxisomal, whereas SOD and GPX activities were mainly cytosolic. Distinct mitochondrial (Mn-SOD) and cytosolic (CuZn-SOD) SOD forms were indicated. Catalase properties were consistent with a catalase, rather than a catalase-peroxidase. The pH-dependence and temperature-dependence of GPX activity were different with H2O2 or CHP as substrate, and these and other observations indicate the existence of a distinct Se-GPX. Under saturating or optimal (GPX) assay conditions, the apparent Michaelis constantsKm (mM) were: catalase, 48 to 68 (substrate, H2O2); Se-GPX, 0.11 (H2O2) and 2.0 (glutathione); and total GPX, 2.2 (eumene hydroperoxide) and 1.2 (glutathione). Calculated catalase activity was 2 to 4 orders of magnitude greater than Se-GPX activity over an [H2O2] of 1 to 1000 μM. The results are discussed in relation to theoretical calculations of in vivo oxyradical production and phylogenetic differences in antioxidant enzyme activities.
321 citations
TL;DR: It is proposed that PROS generated in the brain after CO hypoxia originate primarily from mitochondria, and may contribute to CO-mediated neuronal damage during reoxygenation after severe CO intoxication.
Abstract: To better understand the mechanisms of tissue injury during and after carbon monoxide (CO) hypoxia, we studied the generation of partially reduced oxygen species (PROS) in the brains of rats subjected to 1% CO for 30 min, and then reoxygenated on air for 0-180 min. By determining H2O2-dependent inactivation of catalase in the presence of 3-amino-1,2,4-triazole (ATZ), we found increased H2O2 production in the forebrain after reoxygenation. The localization of catalase to brain microperoxisomes indicated an intracellular site of H2O2 production; subsequent studies of forebrain mitochondria isolated during and after CO hypoxia implicated nearby mitochondria as the source of H2O2. In the mitochondria, two periods of PROS production were indicated by decreases in the ratio of reduced to oxidized glutathione (GSH/GSSG). These periods of oxidative stress occurred immediately after CO exposure and 120 min after reoxygenation, as indicated by 50 and 43% decreases in GSH/GSSG, respectively. The glutathione depletion data were supported by studies of hydroxyl radical generation using a salicylate probe. The salicylate hydroxylation products, 2,3 and 2,5-dihydroxybenzoic acid (DHBA), were detected in mitochondria from CO exposed rats in significantly increased amounts during the same time intervals as decreases in GSH/GSSG. The DHBA products were increased 3.4-fold immediately after CO exposure, and threefold after 120 min reoxygenation. Because these indications of oxidative stress were not prominent in the postmitochondrial fraction, we propose that PROS generated in the brain after CO hypoxia originate primarily from mitochondria. These PROS may contribute to CO-mediated neuronal damage during reoxygenation after severe CO intoxication.
TL;DR: In patients with alcohol‐related severe hepatocellular damage, the oxidative P 450 catalyzed formation of the Me‐DTC and probably also of its sulfoxide and sulphone metabolites is impaired, and thus inactivation of ALDH activity in the liver appears to be delayed or even completely absent.
Abstract: After ingestion, disulfiram (DSF) is rapidly converted, probably in the stomach, to its bis (diethyldithiocarbamato) copper complex. Consequently, absorption and distribution via the gastrointestinal mucosa into the blood might involve both the parent drug and its copper complex. In the blood, both compounds are rapidly degraded to form diethyldithiocarbamic acid (DDC), which is unstable and is further degraded to form diethylamine and carbon disulphide. DDC is also a substrate of phase II metabolism, which involves formation of diethyldithiomethylcarbamate (Me-DDC) and the glucuronic acid of DDC. Me-DDC also undergoes oxidative biotransformation to diethylthiomethylcarbamate (Me-DTC), which is further oxidized to its corresponding sulphoxide and sulphone metabolites. Me-DTC may to act as a suicide inhibitor with a preference for the mitochondrial low Km isozyme of aldehyde dehydrogenases (ALDH 1), whereas the two S-oxidized metabolites, especially the sulfone metabolite, are more potent inhibitors not only of ALDH 1, but also of the cytosolic high Km isozyme of ALDH (ALDH 2). The inhibitory reaction between the enzyme and each of the three metabolites is characterized by a covalent adduct formation, probably with the cysteine residue at the active site of the enzymes. The adduct formed is nonreducible at a physiological concentration of glutathione, and inactivation in the presence of this endogenous tripeptide was increased by action in vitro of the sulphoxide and sulphone metabolites. Those findings are all in concordance with the in vivo observations made on DSF. In human volunteers treated with increasing doses of DSF and challenged with ethanol between each of the dosage periods, the mean plasma concentrations of Me-DTC at steady state were proportional to the DSF doses given. There was also a close relationship between increased oxidative metabolic formation of Me-DTC, high oxidative formation of acetaldehyde, and the full complements of a valid disulfiram ethanol reaction (DER). Consequently, Me-DTC in plasma may not only serve as a marker of the oxidative metabolic function of the liver, but also of the therapeutic effectiveness of the treatment in subjects at steady state. Obviously, there is a need for individual dose-titration regimens. In patients with alcohol-related severe hepatocellular damage, the oxidative P 450 catalyzed formation of the Me-DTC and probably also of its sulfoxide and sulphone metabolites is impaired, and thus inactivation of ALDH activity in the liver appears to be delayed or even completely absent. The consequence for the patient may be an insufficient DER.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: A protective effect of turmeric is document on BP-induced forestomach and DMBA-induced skin tumors in mice, which is dose and time dependent.
Abstract: The anticarcinogenic effect of dietary turmeric on benzo[a]pyrene-(BP) induced forestomach neoplasia and 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin tumorigenesis in female Swiss mice was evaluated. To further elucidate the mechanism of antineoplastic action of turmeric, its effect on the hepatic cytochrome b5, cytochrome P-450, glutathione, and glutathione S-transferase activities was studied in female Swiss mice. Turmeric (2% or 5%) in the diet significantly inhibited the BP-induced forestomach tumors, and this response was dose and time dependent. The 2% turmeric diet significantly suppressed DMBA-induced skin tumors in mice. The 5% turmeric diet for seven consecutive days resulted in a 38% decrease in the hepatic cytochrome b5 and cytochrome P-450 levels. Glutathione content was increased by 12%, and the glutathione S-transferase activity was enhanced by 32% in the liver. Our results document a protective effect of turmeric on BP-induced forestomach and DMBA-induced skin tumors in mice.
TL;DR: The three-dimensional structure of human class pi glutathione S-transferase from placenta (hGSTP1-1), a homodimeric enzyme, has been solved by Patterson search methods and refined at 2.8 A resolution.
TL;DR: In rats, physical exercise caused an increase in blood GSSG levels that were 200% higher after physical exercise than at rest, and antioxidant administration, i.e., oral vitamin C, N-acetyl-L-cysteine, or glutathione is effective in preventing oxidation of the blood glutATHione pool after physical Exercise in rats.
Abstract: We have studied the effect of exhaustive concentric physical exercise on glutathione redox status and the possible relationship between blood glutathione oxidation and blood lactate and pyruvate levels. Levels of oxidized glutathione (GSSG) in blood increase after exhaustive concentric physical exercise in trained humans. GSSG levels were 72% higher immediately after exercise than at rest. They returned to normal values 1 h after exercise. Blood reduced glutathione (GSH) levels did not change significantly after the exercise. We have found a linear relationship between GSSG-to-GSH and lactate-to-pyruvate ratios in human blood before, during, and after exhaustive exercise. In rats, physical exercise also caused an increase in blood GSSG levels that were 200% higher after physical exercise than at rest. GSH levels did not change significantly. Thus, both in rats and humans, exhaustive physical exercise causes a change in glutathione redox status in blood. We have also found that antioxidant administration, i.e., oral vitamin C, N-acetyl-L-cysteine, or glutathione, is effective in preventing oxidation of the blood glutathione pool after physical exercise in rats.
TL;DR: It is not possible to increase circulating glutathione to a clinically beneficial extent by the oral administration of a single dose of 3 g of glutATHione, suggesting that the systemic availability of glutathion is negligible in man.
Abstract: When the plasma glutathione concentration is low, such as in patients with HIV infection, alcoholics, and patients with cirrhosis, increasing the availability of circulating glutathione by oral administration might be of therapeutic benefit.
TL;DR: Endurance training elevated the antioxidant and detoxicant status of muscle and liver, respectively, and total glutathione decreased in the trained leg muscles.
Abstract: 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 per...
TL;DR: It is concluded that glutamine-supplemented nutrition preserves hepatic glutathione, protects the liver, and improves survival during acetaminophen toxicity.
Abstract: Glutathione (GSH) is a major antioxidant that protects tissues from free radical injury. Glutamine augments host defenses and may be important in GSH synthesis. Acetaminophen toxicity causes hepatic GSH depletion and hepatic necrosis. The authors hypothesized that glutamine-supplemented nutrition would enhance liver GSH stores and diminish hepatic injury and death after acetaminophen overdose. Wistar rats received either a standard total parenteral nutrition (TPN) solution (STD) or an isocaloric, isonitrogenous glutamine-supplemented solution (GLN). On the 5th day of feeding, animals were given acetaminophen (400 mg/kg intraperitoneally) and then killed at various time points. Standard TPN solution animals had a rapid depletion of hepatic glutathione, whereas GLN animals were resistant to this drop and rapidly repleted hepatic GSH stores. Glutamine-supplemented animals maintained higher plasma glutamine concentrations, had lesser elevations in hepatic enzymes, and sustained significantly fewer complications compared with STD animals. The authors conclude that glutamine-supplemented nutrition preserves hepatic glutathione, protects the liver, and improves survival during acetaminophen toxicity. Glutamine may augment host defenses by enhancing antioxidant protection.
TL;DR: In vitro species differences in the oxidation of BD and B MO by cytochrome P450-dependent monooxygenases and the inactivation of BMO by epoxide hydrolases and glutathione S-transferases were quantitated using microsomal and cytosolic preparations of livers and lungs obtained from Sprague-Dawley rats, B6C3F1 mice and humans.
Abstract: 1,3-Butadiene (BD), a widely used monomer in the production of synthetic rubber and other resins, is one of the 189 hazardous air pollutants identified in the 1990 Clean Air Act Amendments. BD induces tumors at multiple organ sites in B6C3F1 mice and Sprague-Dawley rats; mice are much more susceptible to the carcinogenic action of BD than are rats. Previous in vivo studies have indicated higher circulating blood levels of butadiene monoepoxide (BMO), a potential carcinogenic metabolite of BD, in mice compared to rats, suggesting that species differences in the metabolism of BD may be responsible for the observed differences in carcinogenic susceptibility. The metabolic fate of BD in humans is unknown. The objective of these studies was to quantitate in vitro species differences in the oxidation of BD and BMO by cytochrome P450-dependent monooxygenases and the inactivation of BMO by epoxide hydrolases and glutathione S-transferases using microsomal and cytosolic preparations of livers and lungs obtained from Sprague-Dawley rats, B6C3F1 mice and humans. Maximum rates for BD oxidation (Vmax) were highest for mouse liver microsomes (2.6 nmol/mg protein/min) compared to humans (1.2) and rats (0.6). The Vmax for BD oxidation by mouse lung microsomes was similar to that of mouse liver but greater than 10-fold higher than the Vmax for the reaction in human or rat lung microsomes. Correlation analysis revealed that P450 2E1 is the major P450 enzyme responsible for oxidation of BD to BMO. Only mouse liver microsomes displayed quantifiable rates for metabolism of BMO to butadiene diepoxide (Vmax = 0.2 nmol/mg protein/min), a known rodent carcinogen. Human liver microsomes displayed the highest rate of BMO hydrolysis by epoxide hydrolases. The Vmax in human liver microsomes ranged from 9 to 58 nmol/mg protein/min and was at least 2-fold higher than the Vmax observed in mouse and rat liver microsomes. The Vmax for glutathione S-transferase-catalyzed conjugation of BMO with glutathione was highest for mouse liver cytosol (500 nmol/mg protein/min) compared to human (45) or rat (241) liver cytosol. In general, the KMs for the detoxication reactions were 1000-fold higher than the KMs for the oxidation reaction. Because of the low solubility of the BD and the relatively high KM for oxidation, it is likely that the Vmax/KM ratio will be important for BD and BMO metabolism in vivo. In vivo clearance constants were calculated from in vitro data for BD oxidation and BMO oxidation, hydrolysis and GSH conjugation.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: It is concluded that rat DVL muscle is particularly vulnerable to exercise-induced free radical damage and that a disturbance of muscle GSH status is indicative of an oxidative stress.
Abstract: Glutathione status and antioxidant enzymes in various types of rat skeletal muscle were studied after an acute bout of exercise (Ex) at different intensities. Glutathione (GSH) and glutathione disulfide (GSSG) concentrations were the highest in soleus (SO) muscle, followed by those in deep (DVL) and then superficial (SVL) portions of vastus lateralis. In DVL, but not in SO or SVL, muscle GSH increased proportionally with Ex intensity and reached 1.8 +/- 0.08 mumol/g wet wt compared with 1.5 +/- 0.03 (P < 0.05) in resting controls (R). GSSG in DVL was increased from 0.10 +/- 0.01 mumol/g wet wt in R to 0.14 +/- 0.01 (P < 0.05) after Ex. Total glutathione (GSH + GSSG) contents in DVL were also significantly elevated with Ex, whereas GSH/GSSG ratio was unchanged. Activities of GSH peroxidase (GPX), GSSG reductase (GR), and catalase (CAT) were significantly higher in SO than in DVL and SVL, but there was no difference in superoxide dismutase activity between the three muscle types. Furthermore, Ex at moderate intensities elicited significant increases in GPX, GR, and CAT activities in DVL muscle. None of the antioxidant enzymes was affected by exercise in SO. It is concluded that rat DVL muscle is particularly vulnerable to exercise-induced free radical damage and that a disturbance of muscle GSH status is indicative of an oxidative stress.
TL;DR: The results indicated that oral administration of NAC protects against LPS toxicity and inhibits the increase in serum TNF levels in LPS-treated mice, and data indicate that GSH can be an endogenous modulator of TNF production in vivo.
TL;DR: The covalent structure of the mixed disulfide of glutaredoxin(C14S) with GSH prepared with 15N-labeling of the protein was confirmed with nuclear magnetic resonance (NMR) spectroscopy, establishing a basis for NMR structural studies of the glutathione binding site on glutared toxin.
Abstract: Glutaredoxin is essential for the glutathione (GSH)-dependent synthesis of deoxyribonucleotides by ribonucleotide reductase, and in addition, it displays a general GSH disulfide oxidoreductase activity. In Escherichia coli glutaredoxin, the active site contains a redox-active disulfide/dithiol of the sequence Cys11-Pro12-Tyr13-Cys14. In this paper, we have prepared and characterized the Cys14----Ser mutant of E. coli glutaredoxin and its mixed disulfide with glutathione. The Cys14----Ser mutant of glutaredoxin is shown to retain 38% of the GSH disulfide oxidoreductase activity of the wild-type protein with hydroxyethyl disulfide as substrate but to be completely inactive with ribonucleotide reductase, demonstrating that dithiol glutaredoxin is the hydrogen donor for ribonucleotide reductase. The covalent structure of the mixed disulfide of glutaredoxin(C14S) with GSH prepared with 15N-labeling of the protein was confirmed with nuclear magnetic resonance (NMR) spectroscopy, establishing a basis for NMR structural studies of the glutathione binding site on glutaredoxin.
TL;DR: The data suggest that the protective mechanisms were mediated by their lipid antiperoxidative activities, which also prevented the glutathione decrease caused by inhibition of peroxide generation.
Abstract: The effects of four calcium channel blockers (nicardipine, nifedipine, verapamil, and diltiazem) on free radical injury in cultured endothelial cells were studied and compared with those of butylated hydroxytoluene. When the cultured cells were exposed to a superoxide and hydroxyl radical generating system for up to 60 minutes, lipid peroxidation occurred, and cellular viability decreased by 60% at 30 minutes. Concomitantly, total cellular glutathione decreased by 40%, whereas total protein thiols changed minimally. Preincubation of the cells with each of the calcium blockers (5 and 20 microM) before free radical addition resulted in various degrees of significant protection against cell death, and losses of glutathione correlated significantly (r = 0.89, p less than 0.001). The order of efficacy was nicardipine greater than nifedipine greater than verapamil greater than diltiazem; butylated hydroxytoluene was about fourfold more potent than nicardipine. Because none of the agents affected the level of hydroxyl radicals generated in the aqueous phase, the data suggest that the protective mechanisms were mediated by their lipid antiperoxidative activities, which also prevented the glutathione decrease caused by inhibition of peroxide generation.
TL;DR: It is concluded that exhaustive exercise can impose a severe oxidative stress on skeletal muscle and that glutathione systems as well as antioxidant enzymes are important in coping with free radical-mediated muscle injury.
Abstract: Glutathione (gamma-glutamylcysteinylglycine) is one of the major antioxidants in the body. The present study investigated the changes of glutathione status, oxidative injury, and antioxidant enzyme systems after an exhaustive bout of treadmill running and/or hydroperoxide injection in male Sprague-Dawley rats. Concentrations of total and reduced glutathione in deep vastus lateralis muscle were significantly increased (P less than 0.01) after exhaustive exercise with either hydroperoxide (t-butyl hydroperoxide) or saline injection, whereas hydroperoxide alone had no significant effect. Exhaustive exercise increased muscle glutathione disulfide content by 75 and 60% (P less than 0.05), respectively, in hydroperoxide and saline groups. Concentrations of glutathione-related amino acids glutamate, cysteine, and aspartate were significantly increased in the same muscle after exhaustion. Hepatic glutathione status was not affected by either hydroperoxide injection or exercise. Glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase activities were significantly elevated after exhaustive exercise with or without hydroperoxide injection in muscle but not in liver. Hydroperoxide and exhaustive exercise enhanced lipid peroxidation in muscle and liver, respectively. It is concluded that exhaustive exercise can impose a severe oxidative stress on skeletal muscle and that glutathione systems as well as antioxidant enzymes are important in coping with free radical-mediated muscle injury.
TL;DR: That the nuclear pool of GSH was found more resistant to depletion by several agents than the cytoplasmic pool supports the assumption that GSH is essential in protecting DNA and other nuclear structures from chemical injury.
Abstract: The intracellular distribution of glutathione (GSH) in cultured hepatocytes has been investigated by using the compound monochlorobimane (BmCl), which interacts specifically with GSH to form a highly fluorescent adduct. Image analysis of BmCl-labeled hepatocytes predominantly localized the fluorescence in the nucleus; the nuclear/cytoplasmic concentration gradient was approximately three. This concentration gradient was collapsed by treatment of the cells with ATP-depleting agents. The uneven distribution of BmCl fluorescence was not attributable to (i) nonspecific interaction of BmCl with protein sulfhydryl groups, (ii) any selective nuclear localization of the GSH transferase(s) catalyzing formation of the GSH-BmCl conjugate, or (iii) any apparent alterations in cell morphology from culture conditions, suggesting that this distribution did, indeed, reflect a nuclear compartmentalization of GSH. That the nuclear pool of GSH was found more resistant to depletion by several agents than the cytoplasmic pool supports the assumption that GSH is essential in protecting DNA and other nuclear structures from chemical injury.
TL;DR: Dissociation between the initiation of alcoholic liver necrosis and enhanced lipid peroxidation is demonstrated, association of enhanced lipidPeroxidation with liver fibrogenesis and depressed antioxidant system is association, and the first demonstration of increased 4‐hydroxynonenal level in experimental alcoholic liver disease is demonstrated.
TL;DR: A progressive and selective depletion of mitochondrial glutathione is demonstrated in the liver in this experimental model of alcoholic liver disease and associated with mitochondrial lipid peroxidation and progression of liver damage.
Journal Article•
TL;DR: The findings demonstrate an increased incidence of low glutathione levels in apparently healthy elderly subjects, who thus may be at risk because of a decreased capacity to maintain many metabolic and detoxification reactions mediated by glutATHione.
TL;DR: The relationship between intracellular glutathione levels and the inducibility of the human heme oxygenase gene after treatment of populations of cultured skin fibroblasts with either UVA radiation or hydrogen peroxide is investigated.
Abstract: Induction of the expression of the mammalian heme oxygenase gene appears to be a general response to oxidant stress. In view of the role of glutathione in protecting cells against solar UVA radiation and other forms of oxidant stress, we have investigated the relationship between intracellular glutathione levels and the inducibility of the human heme oxygenase gene after treatment of populations of cultured skin fibroblasts with either UVA radiation or hydrogen peroxide. We observe a clear relationship between cellular glutathione status and both the constitutive and oxidant-inducible accumulation of heme oxygenase mRNA. Glutathione depletion may lead to enhanced gene expression either as a result of the potentiated accumulation of active oxygen intermediates or as a result of the direct influence of glutathione on a critical target involved in signal transduction.
TL;DR: In this article, the extractable activity of the enzymes of glutathione biosynthesis, γ-glutamylcysteine synthetase (EC 6.3.2) and γglutamic acidity was measured in roots and leaves of maize seedlings (Zea mays L. cv LG 9).
Abstract: Cysteine, γ-glutamylcysteine, and glutathione and the extractable activity of the enzymes of glutathione biosynthesis, γ-glutamylcysteine synthetase (EC 6.3.2.2) and glutathione synthetase (EC 6.3.2.3), were measured in roots and leaves of maize seedlings (Zea mays L. cv LG 9) exposed to CdCl2 concentrations up to 200 micromolar. At 50 micromolar Cd2+, γ-glutamylcysteine contents increased continuously during 4 days up to 21-fold and eightfold of the control in roots and leaves, respectively. Even at 0.5 micromolar Cd2+, the concentration of γ-glutamylcysteine in the roots was significantly higher than in the control. At 5 micromolar and higher Cd2+ concentrations, a significant increase in γ-glutamylcysteine synthetase activity was measured in the roots, whereas in the leaves this enzyme activity was enhanced only at 200 micromolar Cd2+. Labeling of isolated roots with [35S]sulfate showed that both sulfate assimilation and glutathione synthesis were increased by Cd. The accumulation of γ-glutamylcysteine in the roots did not affect the root exudation rate of this compound. Our results indicate that maize roots are at least in part autonomous in providing the additional thiols required for phytochelatin synthesis induced by Cd.