Showing papers on "Glutathione published in 1977"
TL;DR: Glutathione reductase activity is present in spinach chloroplasts and a possible role in chloroplastics is proposed and the pH dependence and substrate concentration for half-maximal rate are reported.
Abstract: Glutathione reductase (EC 1.6.4.2) activity is present in spinach (Spinacia oleracea L.) chloroplasts. The pH dependence and substrate concentration for half-maximal rate are reported and a possible role in chloroplasts is proposed.
594 citations
TL;DR: Multiple forms of glutathione S -transferase, a family of proteins involved both with bilirubin transport and with the detoxification of electrophiles, have been purified from human liver using a scheme which employs an affinity chromatography column prepared by coupling glutathion to epoxy-activated Sepharose.
446 citations
TL;DR: Gel filtration chromatography demonstrated the presence of two peaks of glutathione peroxidase activity assayed with cumene hydroperoxide in the soluble fraction of rat liver, brain, kidney, and testis.
337 citations
TL;DR: It is suggested that there may be at least two pools of glutathione, a labile fraction which probably serves as a reservoir of cysteine which can be released by gamma-glutamyl-transferase when necessary.
Abstract: Rat liver contains a high concentration (7-8mM) of reduced glutathione and its level changes rapidly when starving or feeding rats. We concluded that one of the functions of liver glutathione was to act as a reservoir of cysteine. When starved rats were fed a protein-free diet, the increase in liver glutathione was dependent on the amount of cysteine added to the diet. A cysteine-dependent increase of glutathione was also observed in rats fed a diet containing gelatin with cysteine, but the increase was relatively lowered compared with rats fed a protein-free diet containing the same amount of cysteine. This suppression of the increase in glutathione was observed much more clearly when the gelatin diet was fortified with tryptophan in addition to cysteine. In the presence of tryptophan, L-[35S]-cysteine in the diet appeared to be incorporated primarily into liver and serum proteins, and degradation of liver glutathione must also have been enhanced. Addition of excess cysteine to the diet masked the effects of gelatin and tryptophan, stimulated glutathione synthesis in the liver as well as incorporation of dietary cysteine into protein fractions. Prolonged starvation of rats or injection of dibutyryl-3',5'-cyclic AMP lowered the glutathione level,but the level did not decrease below 2 to 3 mM. These findings suggest that there may be at least two pools of glutathione. A labile fraction, constituting one-third to one-half the total liver glutathione, probably serves as a reservoir of cysteine which can be released by gamma-glutamyl-transferase when necessary.
208 citations
TL;DR: Data obtained in vitro indicate that the cyclopentenone-bearing sesquiterpene lactone and related compounds do not alkylate puring bases of nucleic acids but rather undergo a Michael-type addition reaction with the sulfhydryl groups of reduced glutathione and l-cysteine, which might explain the inhibition of cellular enzyme activities and metabolism that has been observed with Helenalin and tenulin.
Abstract: Helenalin and tenulin injected into CF1 male mice bearing Ehrlich ascites tumors inhibit DNA synthesis and DNA polymerase enzymatic activity in the tumor cells. Helenalin inhibited protein synthesis. Both drugs increased the concentration of adenosine 3',5'-monophosphate, and interfered with glycolytic and mitochondrial energy processes. Cholesterol synthesis was also inhibited, resulting in lower serum cholesterol levels in tumor-bearing animals. Data obtained in vitro indicate that the cyclopentenone-bearing sesquiterpene lactone and related compounds do not alkylate puring bases of nucleic acids but rather undergo a Michael-type addition reaction with the sulfhydryl groups of reduced glutathione and l-cysteine. Thus, the inhibition of cellular enzyme activities and metabolism that has been observed with these drugs might be explained by the occurrence of a Michael-type teaction.
206 citations
TL;DR: It has been found that, in addition to the hexose monophosphate shunt, the mitochondrial NADH-NADP+ transhydrogenase reaction plays an important role in supplying reducing equivalents to the glutathione peroxidase reaction and in maintaining the cellular oxidation-reduction state of the nicotinamide nucleotides.
Abstract: The enhanced reduction of t-butyl hydroperoxide by glutathione peroxidase is accompanied by a decrease in the cellular concentration of both glutathione and NADPH in isolated liver cells, resulting in the release of GSSG (oxidized glutathione) from the perfused rat liver. This phenomenon, first reported by H. Sies, C. Gerstenecker, H. Menzel & L. Flohe (1972) (FEBS Lett. 27, 171-175), can be observed under a variety of conditions, not only with the acceleration of the glutathione peroxidase reaction by organic peroxides, but also during the oxidation of glycollate and benzylamine, during demethylation of aminopyrine in the liver of the phenobarbital-pretreated rat and during oxidation of uric acid in the liver of the starved rat pretreated with 3-amino-1,2,4-triazole. The rate of release of GSSG is altered markedly by changes in the metabolic conditions which affect the rate of hepatic NADPH generation. Thus, regardless of whether achieved by enhanced oxidation of glutathione by glutathione peroxidase or by oxidation of NADPH through other metabolic pathways, an increase in the cellular concentration of GSSG appears to facilitate its release. It has been found that, in addition to the hexose monophosphate shunt, the mitochondrial NADH-NADP+ transhydrogenase reaction plays an important role in supplying reducing equivalents to the glutathione peroxidase reaction and in maintaining the cellular oxidation-reduction state of the nicotinamide nucleotides. Spectrophotometric analysis of the steady-state concentration of the catalase-H2O2 intermediate with simultaneous measurement of the rate of release of GSSG leads to the conclusion that intracellular compartmentation of catalase in the peroxisomes and glutathione peroxidase in the cytosol and mitochondria distinguishes the reactivities of these enzymes one from the other, and facilitates their effective cooperation in hydroperoxide metabolism in the liver.
205 citations
TL;DR: Several findings indicated that glutathione was possibly specifically involved as a coenzyme in the isomerase reaction, but was not oxidized in a stoichiometric quantity.
205 citations
TL;DR: To obtain high levels of glutathione in isolated hepatocytes an isolation procedure shorter than 16 min was used and a common mechanism for these toxic responses is suggested.
Abstract: To obtain high levels of glutathione in isolated hepatocytes an isolation procedure shorter than 16 min was used. This procedure gave a moderately high yield of viable cells (200- 300 x lo6 cells/ 10 g liver) with 44 & 3 nmol of glutathione/106 cells. Incubation in Krebs-Henseleit solution containing 2 % albumin resulted in a continuous loss of reduced glutathione from the cells, while incubation in a medium containing amino acids and horse serum resulted in increased levels, suggesting active synthesis for 5 h. A short and apparently harmless depletion of reduced glutathione was induced by diethylmaleate or cumene hydroperoxide. A depletion of reduced glutathione lasting more than 1 h was accompanied by an increased cellular leakage. The depletion was induced by either diethylmaleate plus paracetamol or diethylmaleate alone in higher concentrations. A common mechanism for these toxic responses is suggested. Glutathione is a thiol that has been implicated in the maintenance of cellular integrity and decreased levels of glutathione in the liver may be either directly or indirectly responsible for cellular damage. Of physiological importance may be the regulation of enzyme function [l ] and protein synthesis [2]. Furthermore glutathione is a substrate for glutathione-peroxidase and may be a significant factor in minimizing the rate of cellular peroxidation [3]. Studies in this laboratory on isolated hepatocytes substantiated this suggestion The toxic effect of the analgesic drug paracetamol
200 citations
TL;DR: The conclusion is that catalase of eye tissues regulates the endogenous H2O2 in eye humors to the physiological level and it is speculated that H 2O2 may be the triggering factor in cataract induced by 3-aminotriazole.
199 citations
TL;DR: This generalized, severe, and specific GSSG-R deficiency caused by therapeutic doses of BCNU may enhance or mediate the toxic and antitumor effects of the nitrosourea and provides a simple yet sensitive biochemical means of monitoring bone marrow reserve in patients receiving multiple courses of chemotherapy with this agent.
178 citations
Journal Article•
TL;DR: Evidence is presented that ligandin and the other glutathione S-transferases reduce the susceptibility of the liver to aminoazo dye-, polycyclic aromatic hydrocarbon-, and aromatic amine-induced carcinogenesis.
Abstract: Summary The glutathione S-transferases are a major group of soluble liver proteins that are involved in the cellular detoxification of electrophilic compounds. Several of these transferases, in particular glutathione S -transferase B or ligandin, interact with chemical carcinogens in vivo . This review presents evidence that ligandin and the other glutathione S -transferases reduce the susceptibility of the liver to aminoazo dye-, polycyclic aromatic hydrocarbon-, and aromatic amine-induced carcinogenesis. Several possible mechanisms by which the transferases reduce hepatocarcinogenesis are proposed. These mechanisms include the direct binding and detoxification of carcinogens by the transferases and the inactivation of steroids and other agents that indirectly stimulate carcinogen activation.
TL;DR: Evidence is presented for the concept that the formation of mixed disulfides of proteins with glutathione is a mechanism for maintenance of a disulfide-sulfhydryl ratio such that the integrity of particulate membranes is maintaine during oxidative and reductive stresses on the hepatic cells.
TL;DR: Hematocytes freshly isolated from diethylmaleate-treated rats have been shown to perform net biosynthesis of intracellular glutathione at approximately an in vivo rate.
TL;DR: Mercapturic acid biosynthesis may be an important route of metabolism of certain isothiocyanates in some mammalian species.
Abstract: 1. The corresponding cysteine conjugate was formed when the GSH (reduced glutathione) or cysteinylglycine conjugates of benzyl isothiocyanate were incubated with rat liver or kidney homogenates. When the cysteine conjugate of benzyl isothiocyanate was similarly incubated in the presence of acetyl-CoA, the corresponding N-acetylcysteine conjugate (mercapturic acid) was formed. 2. The non-enzymic reaction of GSH with benzyl isothiocyanate was rapid and was catalysed by rat liver cytosol. 3. The mercapturic acid was excreted in the urine of rats dosed with benzyl isothiocyanate or its GSH, cysteinyl-glycine or cysteine conjugate, and was isolated as the dicyclohexylamine salt. 4. An oral dose of the cysteine conjugate of [14C]benzyl isothiocyanate was rapidly absorbed and excreted by rats and dogs. After 3 days, rats had excreted a mean of 92.4 and 5.6% of the dose in the urine and faeces respectively, and dogs had excreted a mean of 86.3 and 13.2% respectively. 5. After an oral dose of the cystein conjugate of [C]benzyl isothiocyanate, the major 14C-labelled metabolite in rat urine was the corresponding mercapturic acid (62% of the dose), whereas in dog urine it was hippuric acid (40% of the dose). 5. Mercapturic acid biosynthesis may be an important route of metabolism of certain isothiocyanates in some mammalian species.
TL;DR: Physiochemical and immunological evidence is presented for the identity of the proteins responsible for this enzymatic activity with the glutathione S-transferases (RX:glutathione R-transferase, EC 2.3.5.1.18) that conjugate glutathion with a variety of electrophilic compounds.
Abstract: Soluble, glutathione-stimulated delta 5-3-ketosteroid isomerase (EC 5.3.3.A) activity of human and rat liver resides in very basic proteins with molecular weights of about 45,000 which are present in high concentrations in these tissues. Physiochemical and immunological evidence is presented for the identity of the proteins responsible for this enzymatic activity with the glutathione S-transferases (RX:glutathione R-transferase, EC 2.5.1.18) that conjugate glutathione with a variety of electrophilic compounds. In the rat, the steroid isomerase is associated principally with the major transferase (B), which is also known as ligandin, and has the versatility to bind various hydrophobic compounds such as bilirubin, corticosteroids, and metabolites of a number of carcinogens. Other rat liver-glutathione S-transferase species are far less active in the steroid isomerization reaction. The delta 5-3-ketosteroid isomerase activity of human liver is more uniformly distributed among the five glutathione S-transferases that have been described. Steroid isomerization differs fundamentally from other reactions promoted by glutathione S-transferases in that glutathione is not consumed in the reaction. However, because the transferase enzymes promote nucleophilic attack by glutathione on a variety of largely foreign organic substrates, a similar mechanism may be involved in the isomerase reaction. Delta 5-3-ketosteroids are among the few known naturally occurring substrates for these enzymes.
TL;DR: Preincubation of medium containing ascorbate but no cells, conditions which result in degradation of the vitamin, led to loss of toxicity, indicating that a degradation product was not the lethal agent and that a component of the medium was not converted to a lethal substance.
Abstract: Several types of cultured fibroblasts, including chick embryo, human and mouse, were killed by the addition of sodium ascorbate at final concentrations of 0.05–0.25 mM to cultures at the time of inoculation or to attached cells. Ascorbate did not affect the attachment of cells to the substratum. The effect on chick embryo fibroblasts was visible by fours hours and by six hours almost all cells had swelled and were becoming detached. By 24 hours detached cells had either lysed or become crenated in appearance. Other end-diol reducing agents and also glutathione and cysteine were effective while gulonolactone, a non-reducing analogue of ascorbate, was ineffective. Preincubation of medium containing ascorbate but no cells, conditions which result in degradation of the vitamin, led to loss of toxicity, indicating that a degradation product was not the lethal agent and that a component of the medium was not converted to a lethal substance. The lethal effect of both ascorbate and glutathione was prevented by the addition of catalase to the medium, suggesting that H2O2 formed by intracellular reactions and then excreted into the medium was the cytotoxic agent. This conclusion was supported by the findings that 0.05 mM H2O2 added to chick embryo fibroblasts was lethal and that the effect of this compound on cellular morphology was almost identical to that of ascorbate.
TL;DR: In this paper, the major prostaglandin (PG) biosynthesised by the ram seminal vesicle cyclo-oxygenase from arachidonic acid was 6-keto-PGF1α.
TL;DR: A pathway for the synthesis of dimethyl selenide from sodium selenite was studied in rat liver and kidney fractions under anaerobic conditions in the presence of GSH, a NADPH-generating system, and S-adenosylmethionine and it was concluded that Fraction C contains a methyltransferase acting on small amounts of hydrogen selenides produced non-enzymically by the reaction of selenites with GSH.
TL;DR: It was demonstrated that the sulphydryl compounds β-mercaptoethylamine-HCl, cysteine and methionine significantly increased the survival rate of mice given a lethal dose of ethanol.
TL;DR: Dehydroascorbate reductase was detected in the leaves of several plants and has been partially purified from spinach leaves and has a MW of ca 25 000 and Cysteine cannot replace GSH as a donor.
TL;DR: By adding vitamin E the cells survived over 6 days in cystine-free medium, though glutathione content of the cells was reduced to less than 1% of the normal level, though synthetic antioxidants had similar effect.
TL;DR: The findings indicate that glucocorticoid binding activity of lung and many other tissues decays rapidly in vitro due to oxidation of receptor sulfhydryl groups.
Abstract: We examined the levels and stability of glucocorticoid receptor activity in cytosol preparations of rat lung and other tissues. [3H]Dexamethasome binding capacity at 2 C in lung cytosol decreases with a t1/2 of 40 min in the absence of steroid or a sulfhydryl compound. This rapid inactivation of unbound receptor is prevented and reversed by addition of a sulfhydryl compound (t1/2 = 22h); maximal binding occurs with 2 mM dithiothreitol (DTT), or with 20-25 mM mercaptoethanol, thioglycerol or glutathione. Binding activity is also stabilized by formation of the receptor-steroid complex; dissociation of the complex occurs at the same rate (t1/2 = 18.6h) in both the presence and absence of DTT. In the presence of DTT, cytosol of adult rat lung specifically binds 0.82 pmol of [3H]dexamethasone per mg protein (average 19,000 sites per cell) with an equilibrium dissociation contant of 2.5 nM at 2 C. At 37 C, dispersed lung cells show specific nuclear binding of hormone. DTT also increased dexamethasone binding activity in cytosol prepared from lung of adult hamster, adult mouse, fetal monkey and 11 of 15 tissues of adult rat. There was a minimal effect of DTT in reactions using cytosol of fetal rat lung, fetal and newborn human lung, rabbit lung, and liver, kidney, heart and testis of adult rat. Liver contains a heat-stable factor which mimics that stabilizing effect of DTT. The variable requirement for DTT may reflect in part tissue concentrations of endogenous sulfhydryl compounds. Our findings indicate that glucocorticoid binding activity of lung and many other tissues decays rapidly in vitro due to oxidation of receptor sulfhydryl groups. Maintenance of these groups in the reduced form by endogenous tissue factors, addition of sulfhydryl compounds, or binding of glucocorticoid stabilizes receptor and allows its detection in lung and other tissues previously found to contain little if any activity.
TL;DR: Comparisons between normal RBC and vitamin E-deficient RBC suggest that vitamin E has little effect on the inward diffusion of extra-cellular H(2)O(2).
TL;DR: A proof of the existence of SOD, the enzyme which dismutates O2 – to relatively less toxic H2O2, has been obtained for the first time in the case of lens and cornea.
Abstract: Studies have been conducted to determine the mechanisms by which rat ocular tissues may protect themselves against the toxic reactions initiated by superoxide radicals Such radicals may be formed in the transparent ocular tissues by photochemical as well as metabolic oxidations A proof of the existence of SOD, the enzyme which dismutates O2 – to relatively less toxic H2O2, has been obtained for the first time in the case of lens and cornea The activity of the enzyme in lens was lower as compared to that in cornea and retina The amount of protein giving an activity of one unit varied between 456–600 μg in cornea and 45–92 μg in retina It is possible that the low activity of SOD in the lens is compensated for by high ascorbate and glutathione Ascorbate effectively scavenged the superoxide radicals at 10––6 m The effectiveness of glutathione was also observed to lie in the same range
TL;DR: Observations explain why cyanide inhibition of glutathione peroxidase has not been noted previously and provide new approaches for studying the chemical nature of the enzyme-selenium.
TL;DR: It is concluded that binding of the reactive metabolite of paracetamol to hepatocyte macromolecules need not lead to hepatic necrosis provided that sulphydryl groups are present in the liver to prevent the deleterious effects of such binding.
TL;DR: Support for this idea is provided by the close temporal correlation between the diurnal variations in cyclic AMP, hepatic catalase, peroxide generation and GSSProt-GSH levels.
TL;DR: The observation that benzo(a)pyrene 4,5-oxide was a very good substrate for the cytosol localized glutathione S-transferase, but that it was not inactivated by this system when bacteria and microsomes were in direct contact, indicates that a severe limitation for the inactivation of benzo (a) pyrene metabolites by this enzyme is imposed by its localization in the cytOSol.
Abstract: Benzo(a)pyrene was activated to metabolites mutagenic for Salmonella typhimurium TA 98 by liver microsomes from control and phenobarbital treated mice. Under these conditions benzo(a)pyrene 4,5-oxide accounts for most of the mutagenicity. We have therefore investigated (1) the conjugation of benzo(a)pyrene 4,5-oxide with glutathione and (2) the effect of glutathione on the mutagenicity of benzo(a)pyrene.
TL;DR: A quantitative method for the estimation of the glutathione, Cysteine, and N -acetyl cysteine conjugates of acetaminophen obtained from microsomal incubations has been developed using high-pressure liquid chromatography (HPLC).