Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GLUTATHIONE REDUCTASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1983

Depressed erythrocyte glutathione reductase activity in sickle cell disease.

In a group of 27 sickle cell disease patients ranging in age from 2 yr 3 months to 43 yr, 13 (48%) were found to have depressed erythrocyte glutathione reductase activity suggesting riboflavin deficiency. Glutathione reductase activity coefficients did not correlate with riboflavin intakes which were calculated from 3-day diet records returned by 16 patients. Other causes of riboflavin deficiency including decreased absorption, altered metabolism, or increased excretion of the vitamin must be considered. The potential effect of depressed erythrocyte glutathione reductase activity in the sickle cell disease process is discussed.

Adolescent↗
PubMed1977

Purification by affinity chromatography of yeast glutathione reductase, the enzyme responsible for the NADPH-dependent reduction of the mixed disulfide of coenzyme A and glutathione.

Glutathione reductase (NAD(P)H : oxidised-glutathione oxidoreductase, EC 1.6.4.2) was purified from baker's yeast by a new procedure involving affinity chromatography on 2',5'-ADP-Sepharose 4B. The yield was 65% of essentially homogeneous enzyme. The activity was assayed with both glutathione disulfide (GSSG) and the mixed disulfide of coenzyme A and glutathione (CoAssg). The two disulfide substrates gave coinciding activity profiles and a constant ratio of the activities in different chromatographic and electrophoretic systems. No evidence was obtained for the existence of a reductase specific for CoASSG distinct from glutathione reductase. It is concluded that normal baker's yeast contains a single reductase active with both GSSG and CoASSG.

Adenosine Diphosphate↗
PubMed1995

Glutathione reductase and lipoamide dehydrogenase have opposite stereospecificities for alpha-lipoic acid enantiomers.

The reduction of exogenous alpha-lipoic acid to dihydrolipoate by mammalian cells and tissues confers additional antioxidant protection to the cell. Both (R+) and (S-) isomers of alpha-lipoic acid were analyzed as substrates with glutathione reductase from several sources and with mammalian lipoamide dehydrogenase. Mammalian glutathione reductase catalyzed faster reduction of (S)-lipoic acid (1.4-2.4-fold greater activity) than of (R)-lipoic acid, whereas lipoamide dehydrogenase had a very marked preference for (R)-lipoic acid (18-fold greater activity) over (S)-lipoic acid. Mammalian glutathione reductase showed better affinity for (S)-lipoic acid substrate; Km values were 3.5 mM for (S)-lipoic acid and and 7 mM for (R)-lipoic acid. Glutathione reductase from yeast reduced lipoic acid less efficiently than the mammalian enymes, had a Km for both stereoisomers of about 10 mM, and showed little stereospecificity. Although (S)-lipoic acid is not formed in nature, these findings indicate that exogenous (S)-lipoic acid may have a useful role as an antioxidant for mammalian systems.

Animals↗
PubMed1987

Effect of whole body gamma-radiation on glutathione reductase of rat tissues.

Adult female Sprague Dawley rats approximate ten months old were exposed to whole body gamma radiation of sublethal (4 Gy) and lethal (10 Gy) doses of radiation. Serum glutathione reductase enzyme values of 4 Gy exposed rats did not show any change on first and fourth day but significantly decreased on eighth day, while enzyme values in 10 Gy exposed group remained unaltered throughout. Heart glutathione reductase activities of sublethal group did not show any change on first and eighth day but significantly decreased on fourth day. Rats exposed to lethal doses of radiation, enzyme activities remained unchanged throughout. Liver glutathione reductase enzyme values of 4 Gy exposed group showed significant decrease on first and fourth day but arrived at control values on eighth day while the same in 10 Gy exposed group showed significant decrease from first day till the eighth day. An appreciable diminution was observed in spleen glutathione reductase enzyme activities of sublethal and lethal exposed rats from first day till eighth day.

Animals↗
PubMed1998

Rhythms of glutathione peroxidase and glutathione reductase in brain of chick and their inhibition by light.

Melatonin was recently shown to be a component of the antioxidative defense system of organisms due to its free radical scavenging and antioxidant activities. Pharmacologically, melatonin stimulates the activity of the peroxide detoxifying enzyme glutathione peroxidase in rat brain and in several tissues of chicks. In this report, we studied the endogenous rhythm of two antioxidant enzymes, glutathione peroxidase and glutathione reductase, in five regions (hippocampus, hypothalamus, striatum, cortex and cerebellum) of chick brain and correlated them with physiological blood melatonin concentrations. Glutathione peroxidase exhibited a marked 24 h rhythm with peak activity in each brain region which had acrophases about 8 h after lights off and about 4 h after the serum melatonin peak was detected. Glutathione reductase activity exhibited similar robust rhythms with the peaks occurring roughly 2 h after those of glutathione peroxidase. We suggest that neural glutathione peroxidase increases due to the rise of nocturnal melatonin levels while glutathione reductase activity rises slightly later possibly due to an increase of its substrate, oxidized glutathione. The exposure of chicks to constant light for 6 days eliminated the melatonin rhythm as well as the peaks in both glutathione peroxidase and glutathione reductase activities. These findings suggest that the melatonin rhythm may be related to the nighttime increases in the enzyme activities, although other explanations cannot be excluded.

Animals↗
PubMed2000

Mixed disulfide with glutathione as an intermediate in the reaction catalyzed by glutathione reductase from yeast and as a major form of the enzyme in the cell.

Glutathione reductase catalyzes the reduction of glutathione disulfide by NADPH. The FAD of the reductase is reduced by NADPH, and reducing equivalents are passed to a redox-active disulfide to complete the first half-reaction. The nascent dithiol of two-electron reduced enzyme (EH(2)) interchanges with glutathione disulfide forming two molecules of glutathione in the second half-reaction. It has long been assumed that a mixed disulfide (MDS) between one of the nascent thiols and glutathione is an intermediate in this reaction. In addition to the nascent dithiol composed of Cys(45) and Cys(50), the enzyme contains an acid catalyst, His(456), having a pK(a) of 9.2 that protonates the first glutathione (residue numbers refer to the yeast enzyme sequence). Reduction of yeast glutathione reductase by glutathione and reoxidation of EH(2) by glutathione disulfide indicate that the mixed disulfide accumulates, in particular, at low pH. The reaction of glutathione disulfide with EH(2) is stoichiometric in the absence of an excess of glutathione. The equilibrium position among E(ox), MDS, and EH(2) is determined by the glutathione concentration and is not markedly influenced by pH between 6.2 and 8.5. The mixed disulfide is the principal product in the reaction of glutathione with oxidized enzyme (E(ox)) at pH 6. 2. Its spectrum can be distinguished from that of EH(2) by a slightly lower thiolate (Cys(50))-FAD charge-transfer absorbance at 540 nm. The high GSH/GSSG ratio in the cytoplasm dictates that the mixed disulfide will be the major enzyme species.

Catalysis↗
PubMed1995

Catalase and glutathione reductase protection of human alveolar macrophages during oxidant exposure in vitro.

Because alveolar macrophages generate and release reactive oxygen metabolites but also contain antioxidative enzymes, they have the potential of either damaging or protecting tissues. We investigated the relative role of the hydrogen peroxide (H2O2)-scavenging antioxidative enzymes in H2O2 disposal and cell protection using freshly isolated (5 h ex vivo) and overnight (24 h ex vivo) cultured human alveolar macrophages. Cell protection was assessed on the basis of maintenance of cellular high-energy phosphates, leakage of intact nucleotides into the extracellular medium, and appearance of the nucleotide catabolic products xanthine, hypoxanthine, and uric acid. To investigate the relative importance of catalase and the glutathione redox cycle, the experiments were conducted in cells pretreated with amino-triazole (ATZ) to inactivate catalase or with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) to inactivate glutathione reductase. Catalase, glutathione peroxidase, and glutathione reductase activities did not change significantly during overnight culture of the cells. Both freshly isolated and cultured cells consumed exogenous H2O2 mainly by the catalase-dependent pathway. When the cells were exposed to H2O2 (100 microM), catalase and the glutathione redox cycle equally participated in maintaining cellular high-energy nucleotides. However, when cultured cells were exposed to formylated peptide (FMLP) (10(-7) M), the glutathione redox cycle was responsible for the maintenance of high-energy nucleotides. Furthermore, in both exposures, the glutathione redox cycle was more important in maintaining cell membrane integrity and preventing nucleotide leakage from the cells. Immunocytochemical labeling showed that catalase was primarily localized in the peroxisomal compartment of these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed2000

Deletion of the parasite-specific insertions and mutation of the catalytic triad in glutathione reductase from chloroquine-sensitive Plasmodium falciparum 3D7.

The flavoenzyme glutathione reductase (GR; NADPH+glutathione disulphide+H(+)-->NADP(+)+2 glutathione-SH) of Plasmodium falciparum is a promising drug target against tropical malaria. As P. falciparum genes are assumed to be highly polymorphic we have cloned and expressed the GR cDNA of the chloroquine-sensitive strain 3D7. In comparison to the known GR of the chloroquine-resistant K1 strain there are three base exchanges all of them leading to amino acid substitutions (residues 281, 285 and 335). The catalytic efficiency k(cat)/K(m) of the 3D7 enzyme is 5-fold lower than for the K1 enzyme. In contrast, vis-à-vis the drugs carmustine, methylene blue and fluorophenyliso-alloxazine the two enzyme species exhibited identical inhibition kinetics. Two structural motifs which are specific for P. falciparum GR were studied by mutational deletion analysis of 3D7 GR. Loop 126-138 appears to be important for folding and stability of the enzyme, whereas the subdomain 318-350 was found to be involved in FAD-binding. The subdomain has no major influence on the known functions of the catalytic triad Cys-40, Cys-45 and His-485'. Flavin absorption spectroscopy of inactive point mutants showed that Cys-45 forms a thiolate charge transfer complex and Cys-40 is the interchange thiol, which reduces glutathione disulphide. The mutant His-485-->Gln had a normal K(m) for glutathione disulphide reduction but only 0.8% residual catalytic activity when compared with wild-type GR, which confirms its function as an acid/base catalyst. The parasite-specific domains in combination with the reactive catalytic residues appear to be a suitable target matrix for inhibiting GR in vivo.

Amino Acid Sequence↗
PubMed1979

Mechanism of inhibition of red blood cell glutathione reductase activity by BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea).

A study of the mechanism of inhibition of glutathione reductase activity by BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea) demonstrated that the enzyme was protected from inhibition by mercaptoethanol. N-Ethylmaleimide competes with BCNU and also protects the enzyme from inhibition. The inhibited enzyme showed decreased affinity for NADPH. Our data suggest that the inhibition of glutathione reductase is due to an alteration of the redox state. Several other red cell enzymes were inhibited by high concentrations of BCNU; these enzymes were also protected by mercaptoethanol. Among alkylating agents tested, only BCNU inhibited glutathione reductase at therapeutic levels.

Carmustine↗
PubMedDate not supplied

Isoniazid acetylating phenotype in patients with paracoccidioidomycosis and its relationship with serum sulfadoxin levels, glucose-6-phosphate dehydrogenase and glutathione reductase activities.

The authors evaluated the isoniazid acetylating phenotype and measured hematocrit, hemoglobin, glucose-6-phosphate dehydrogenase and glutathione reductase activities plus serum sulfadoxin levels in 39 patients with paracoccidioidomycosis (33 males and 6 females) aged 17 to 58 years. Twenty one (53.84%) of the patients presented a slow acetylating phenotype and 18(46.16%) a fast acetylating phenotype. Glucose-6-phosphate-dehydrogenase (G6PD) activity was decreased in 5(23.80%) slow acetylators and in 4(22.22%) fast acetylators. Glutathione reductase activity was decreased in 14(66.66%) slow acetylators and in 12(66.66%) fast acetylators. Serum levels of free and total sulfadoxin were higher in slow acetylator (p less than 0.02). Analysis of the results permitted us to conclude that serum sulfadoxin levels are related to the acetylator phenotype. Furthermore, sulfadoxin levels were always above 50 micrograms/ml, a value considered therapeutic. Glutathione reductase deficiency observed in 66% of patients may be related to the intestinal malabsorption of nutrients, among them riboflavin, a FAD precursor vitamin, in patients with paracoceidioidomycosis.

Acetylation↗
PubMedDate not supplied

[Glutathione reductase activity in erythrocytes of rats with transplantable Morris 5123 hepatoma].

The activity of NADPH- and NADH-dependent erythrocyte glutathione reductase was determined in rats with Morris 5123 hepatoma at different stages of tumor development (10, 20, 30 and 40 days after transplantation). During the early stage of tumor growth the activity of glutathione reductase with either of these coenzymes was increased. In the late stage of the disease the activity of NADPH-dependent glutathione reductase fell below control values. The obtained results are discussed in the light of previous observations on the effects of this neoplasm on the metabolism of erythrocytes.

Animals↗
PubMed1993

Glutathione status and glutathione reductase activity in spruce needles of healthy and damaged trees at two mountain sites.

Levels of glutathione, in both reduced and oxidized form, and glutathione reductase activity were monitored in needles of healthy and damaged spruce trees (Picea abies (L.) Karst.) during the course of four vegetation periods at two natural sites. The glutathione content and glutathione reductase activity showed a pronounced annual rhythm in undamaged trees, whereas damaged spruce trees deviated significantly from this course. In comparison with undamaged trees, damaged trees showed markedly increased levels of glutathione during the test period of 1989-1991. However, glutathione reductase activity differed in damaged and undamaged trees, only in 1989-1990. The ratio of reduced to oxidized glutathione (GSH/GSSG ratio) was slightly higher in damaged trees, and the highest levels were found during the winter months. In the case of damaged trees, a correlation between GSH/GSSG ratio and current ozone levels at the sites could be clearly established. The present results indicate that damaged trees suffer from increased oxidative stress, especially in the period from June to October.

Journal Article↗
PubMed1986

Activity of glutathione peroxidase and glutathione reductase in the human lens related to age.

Lenses from 42 eye bank eyes were assayed for glutathione peroxidase and glutathione reductase activities. The activity of glutathione peroxidase, when considered as a function of age, was lowest in the neonate lens, increasing with age to reach maximal values in young adult lenses, and thereafter progressively decreasing with ages greater than 40 years. Glutathione reductase activity was little affected by age when expressed as activity per lens, per gram lens or per mg soluble protein, indicating that activity of this enzyme did not increase with lens size as would a representative lenticular protein. However, the activity of this enzyme per gram lens was among the highest of any species yet examined.

Adolescent↗
PubMed1992

Glutathione reductases from a variety of sources are inhibited by physiological levels of glutathione.

1. Glutathione reductase from human platelets, bovine intestinal mucosa, yeast and E. coli were inhibited in vitro by physiological levels of reduced glutathione with IC50s of 6.61 mM, 2.92 mM, 2.40 mM and 12.11 mM, respectively. 2. A steady-state kinetic examination revealed that glutathione inhibited the NADPH oxidation (at constant [glutathione-disulphide]) catalysed by the eucaryotic enzymes uncompetitively, whereas the E. coli enzyme appeared unaffected by glutathione concentrations of up to 10 mM. 3. With respect to glutathione inhibition of glutathione-disulphide reduction (at constant [NADPH]), the human enzyme was inhibited uncompetitively; the bovine and yeast enzymes displayed apparent mixed hyperbolic inhibition; the E. coli enzyme was inhibited competitively.

Animals↗
PubMed1997

A high-sensitivity, single-gel, polyacrylamide gel electrophoresis method for the quantitative determination of glutathione reductases.

A new method is described that allows the selective staining and quantification of gluthathione reductases (EC 1.6.4.2) in cell extracts following acrylamide gel electrophoresis. The method is based on modifications of two previous procedures; it uses DTNB [5,5'-dithiobis(2-nitrobenzoic acid)] to develop a yellow color on reaction with GSH formed from the NADPH-dependent reduction of oxidized glutathione. This is followed by specific counterstaining of glutathione reductase with dichlorophenolindophenol/nitroblue tetrazolium. The use of DTNB in the initial staining step inhibits enzymes other than glutathione reductase that could be stained with the dichlorophenolindophenol/nitroblue tetrazolium counterstain. Enzymes such as thioredoxin reductase, which can directly reduce DTNB with NADPH, may be nonselectively stained by this new procedure. Plant ferredoxin-thioredoxin reductase is not reduced by NADPH and therefore does not appear. Glutathione reductase stains much quicker with DTNB in the presence of GSSG than with thioredoxin reductase, allowing them to be distinguished, if parallel gels are run without GSSG, where the two enzymes react at the same rate. The sequential use of two staining procedures results in distinct, sharp permanent bands that can be used to quantify the activity of glutathione reductase while precluding artifacts generated by the previous methods.

2,6-Dichloroindophenol↗
PubMed2000

Characterisation of pea cytosolic glutathione reductase expressed in transgenic tobacco.

Expression in transgenic tobacco (Nicotiana tabacum L.) of a pea (Pisum sativum L.) GOR2 cDNA, encoding an isoform of glutathione reductase (GOR2), resulted in a 3- to 7-fold elevation of total foliar glutathione reductase (GR) activity. The enzyme encoded by GOR2 was confirmed to be extraplastidial in organelle fractionation studies and was considered most likely to be localised in the cytosol. A partial purification of GOR2 was achieved but a standard affinity chromatography step, using adenosine-2',5'-diphosphate-Sepharose and often employed in the purification of GR from diverse sources, was unsuccessful with this isoform. Preparative isoelectric focussing was employed as part of the purification procedure of GOR2 and a complete separation from plastidial/mitochondrial glutathione reductase (GOR1) was achieved. The isoform GOR2 was shown to have a slower migration on non-denaturing polyacrylamide gels compared with GOR1 and properties typical of GR enzymes from plant sources.

Cytosol↗
PubMed1986

Glutathione reductase from Escherichia coli: cloning and sequence analysis of the gene and relationship to other flavoprotein disulfide oxidoreductases.

A glutathione reductase negative strain of Escherichia coli K-12 was isolated as a thermoresistant survivor when a gor::MuctsAp lysogen was subjected to elevated temperature. It was found that in addition to being ampicillin sensitive this mutant was hypersensitive to arsenate, which may be connected with the fact that the gor gene maps between 77 and 78 min on the E. coli genome, close to the pit locus encoding the major arsenate transport system of E. coli. A derivative of this mutant was used as the recipient in a screen of the Clarke and Carbon hybrid plasmid bank of E. coli DNA. A plasmid, pGR, was isolated that encodes both an arsenate-resistance element and glutathione reductase. Restriction mapping of this plasmid showed that the insert DNA is approximately 10 kilobase pairs in length, and a fragment of the gor gene was identified that allowed the gor gene to be accurately mapped on pGR by a combination of restriction analysis and Southern blotting. The DNA sequence of the gor gene was determined and found to encode a protein of 450 amino acid residues. The glutathione reductase of E. coli is very homologous to the human enzyme and is also related (though less closely) to other flavoprotein disulfide oxidoreductases whose sequences are available. These enzymes have retained a common mechanism while evolving different specificities.

Amino Acid Sequence↗
PubMed1990

Glutathione reductase: comparison of steady-state and rapid reaction primary kinetic isotope effects exhibited by the yeast, spinach, and Escherichia coli enzymes.

Kinetic parameters for NADPH and NADH have been determined at pH 8.1 for spinach, yeast, and E. coli glutathione reductases. NADPH exhibited low Km values for all enzymes (3-6 microM), while the Km values for NADH were 100 times higher (approximately 400 microM). Under our experimental conditions, the percentage of maximal velocities with NADH versus those measured with NADPH were 18.4, 3.7, and 0.13% for the spinach, yeast, and E. coli enzymes, respectively. Primary deuterium kinetic isotope effects were independent of GSSG concentration between Km and 15Km levels, supporting a ping-pong kinetic mechanism. For each of the three enzymes, NADPH yielded primary deuterium kinetic isotope effects on Vmax only, while NADH exhibited primary deuterium kinetic isotope effects on both V and V/K. The magnitude of DV/KNADH at pH 8.1 is 4.3 for the spinach enzyme, 2.7 for the yeast enzyme, and 1.6 for the E. coli glutathione reductase. The experimentally determined values of TV/KNADH of 7.4, 4.2, and 2.2 for the spinach, yeast, and E. coli glutathione reductases agree well with those calculated from the corresponding DV/KNADH using the Swain-Schaad expression. This suggests that the intrinsic primary kinetic isotope effect on NADH oxidation is fully expressed. In order to confirm this conclusion, single-turnover experiments have been performed. The measured primary deuterium kinetic isotope effects on the enzyme reduction half-reaction using NADH match those measured in the steady state for each of the three glutathione reductases.(ABSTRACT TRUNCATED AT 250 WORDS)

Deuterium↗