Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.2.3 (glutathione synthetase)
 678 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A loss of glutathione from the kidney can cause increased sensitivity to oxygen free radical-induced injury. In this study we investigated the effects of kidney preservation on glutathione and how various glutathione precursors affect glutathione concentration in the dog kidney. During 5-day continuous machine perfusion of the kidney at 5 degrees C, a loss of glutathione from the cortex tissue was seen (24% +/- 1% glutathione remained after 5 days). Perfusion with reduced glutathione (GSH, 3 mmol/L) suppressed this loss (77% +/- 11% of glutathione remained after 5 days). Oxidized glutathione (GSSG) did not prevent the loss of glutathione. The addition of the three amino acids that make up glutathione (glycine, glutamic acid, and cysteine, 3 mmol/L each) also suppressed the loss of glutathione (82% +/- 13% remained at 5 days). The glutathione precursor, thioproline, a cysteine delivery compound, in combination with glycine and glutamic acid (3 mmol/L each), stimulated the synthesis of glutathione in the kidney during hypothermic perfusion (137% +/- 23% of control values at 5 days). The increase in tissue glutathione stimulated by GSH or other precursors was sensitive to the glutathione synthetase inhibitor, buthionine sulfoximine. This indicated the existence of active glutathione metabolism even at 5 degrees C in perfused kidneys. This study showed that in kidney preservation a loss of glutathione occurred that could be suppressed by the addition of various precursors for glutathione synthesis. The loss of glutathione from preserved kidneys may be one cause of posttransplant renal injury that could be prevented by use of the appropriate glutathione precursors.
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PMID:Changes in glutathione concentration in hypothermically perfused dog kidneys. 199 54

Isolated hepatocytes suspended in a liver preservation solution (University of Wisconsin (UW) solution) and exposed to cold (5 degrees C) ischemia lose viability (LDH release) after 3 (76.5 +/- 2.6% extracellular LDH) and 4 days (90.3 +/- 5.7% extracellular LDH) storage when rewarmed (37 degrees C) in Krebs-Henseleit buffer. However, if 3 mM glycine is added to Krebs-Henseleit buffer the loss of LDH on rewarming was suppressed (% LDH = 24.4 +/- 2.2% and 33.2 +/- 3.0%, at 3 and 4 days, respectively). The protection by glycine could also be obtained by storing the hepatocytes in the UW solution containing 15 mM glycine and rewarming in the absence of glycine in Krebs-Henseleit buffer. There did not appear to be a relationship between the protection by glycine and glutathione concentration of the hepatocytes as shown by the lack of effect of a glutathione synthetase inhibitor (butathionine sulfoximine) on the protective effects of glycine. Other amino acids did not provide protection to hepatocytes exposed to cold ischemia. The mechanism of action of glycine is not known, but this compound may be important in improving cold storage of livers for transplantation.
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PMID:Glycine prevention of cold ischemic injury in isolated hepatocytes. 201 58

Small metal-binding peptides, cadystins, with the general structure of (gamma-Glu-Cys)n-Gly ((gamma EC)nG), were synthesized in a cell-free system of fission yeast to examine the in vivo synthetic pathway. The crude enzyme for cadystin synthesis was prepared by ammonium sulfate precipitation (75% saturation) from the 120,000 x g supernatant of the cell extract, and the excess salt in the enzyme fraction was removed by Sephadex gel filtration. Using this crude enzyme fraction, it was shown that there were two pathways for cadystin biosynthesis. One pathway is gamma-Glu-Cys (gamma EC) dipeptidyl transfer from both glutathione (gamma ECG) and cadystins to glutathione and cadystins. The other one is gamma EC polymerization from (gamma EC)n and glutathione to (gamma EC)n + i, followed by glycine addition with glutathione synthetase.
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PMID:Two pathways in the biosynthesis of cadystins (gamma EC)nG in the cell-free system of the fission yeast. 203 14

3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase catalyses the rate-limiting step in cholesterol synthesis. Glutathione (GSH) has been postulated to be an important activator of HMG-CoA reductase in vivo. HMG-CoA reductase activity was assayed in cultured fibroblasts from healthy children. Solubilized enzyme preparations were prepared by ultracentrifugation after freezing and thawing of fibroblasts. Such treatment increased the relative enzyme activity markedly. Enzymological assay conditions were established. Addition of GSH stimulated the reaction, whereas there was inhibition after addition of glutathione disulphide (GSSG). The inhibitory effect of GSSG could be reversed by the addition of excess GSH. Fibroblast preparations, deficient in GSH, were obtained from children with glutathione synthetase deficiency or from normal subjects after the growth of fibroblasts in the presence of buthionine sulphoximine. Solubilized enzyme preparations from GSH-deficient fibroblasts had HMG-CoA reductase activities lower than or comparable with those of control preparations. The results indicate only some reduction in the capacity for cholesterol synthesis in subjects with glutathione deficiency. The existence of additional activation mechanisms in vivo, alternative to GSH, for thiol-dependent modulation of HMG-CoA reductase activity seems likely.
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PMID:Cholesterol synthesis in patients with glutathione deficiency. 212 8

In a therapeutic trial, the effect of short-term low-dosage N-acetylcysteine supplementation on glutathione metabolism was investigated in two patients with hereditary glutathione deficiency (5-oxoprolinuria). Clinical and neurophysiological examinations of the patients indicated progressive neurological damage. The pretreatment concentrations of total and free glutathione in leukocytes were 15-20% of normal, whereas the corresponding gamma-glutamylcysteine levels were increased. In plasma, the glutathione concentrations were similarly decreased, but no gamma-glutamylcysteine was detected. Total glutathione in erythrocytes was markedly decreased. Low urinary excretion of cysteinylglycine, cyst(e)ine, taurine, N-acetylcysteine, mercaptolactate and mercaptoacetate and reduced leukocyte taurine levels constituted additional evidence of decreased intracellular availability of cysteine, i.e. glutathione. Oral supplementation with N-acetylcysteine (5 mg/kg x 3/day) had no effect on acid-base balance, erythrocyte glutathione levels or 5-oxoproline concentrations in plasma and urine. In leukocytes, the glutathione concentrations were increased by 20-30%, whereas the gamma-glutamylcysteine levels were essentially unaltered. In parallel, the urinary excretion of cysteinylglycine was increased and the leukocyte levels and urinary outputs of sulphur amino acids were restored. No side-effects of the treatment were noted. The results indicate that N-acetylcysteine may be of value in increasing the low intracellular glutathione concentrations and cysteine availability in patients with hereditary glutathione synthetase deficiency.
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PMID:A therapeutic trial with N-acetylcysteine in subjects with hereditary glutathione synthetase deficiency (5-oxoprolinuria). 250 72

A strain of Escherichia coli, enriched in its content of gamma-glutamylcysteine synthetase and glutathione synthetase activities by recombinant DNA techniques, is more resistant to the lethal effects of gamma-irradiation than is the corresponding wild strain. Although the gene-enriched strain has higher glutathione levels than the wild strain, the observed radioresistance appears to be associated with the increased capacity of the gene-enriched strain to synthesize glutathione when irradiated rather than to the cellular levels of glutathione per se. Thus, resistance was abolished in the presence of buthionine sulfoximine, a selective inactivator of gamma-glutamylcysteine synthetase that decreases glutathione synthesis but that does not act directly to lower cellular glutathione levels. Conclusions drawn from studies on this E. coli model system may have relevance to protection of mammalian cells by glutathione.
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PMID:Increased capacity for glutathione synthesis enhances resistance to radiation in Escherichia coli: a possible model for mammalian cell protection. 256 2

The metabolism of glutathione and activities of its related enzymes were studied in erythrocytes from patients with non-insulin-dependent diabetes mellitus (NIDDM). A decrease in the levels of the reduced form of glutathione and an increase in the levels of glutathione disulfide were found in erythrocytes of diabetics. To elucidate these changes in the levels of glutathione, synthetic and degradative processes were studied. The activity of gamma-glutamylcysteine synthetase was significantly lower in diabetics than in normal controls. The activity of glutathione synthetase of each group was the same. The rate of outward transport of glutathione disulfide in diabetics decreased to approximately 70% of that of normal controls. The activity of glutathione reductase decreased in diabetics. These data suggest that the decrease in the levels of reduced form of glutathione in erythrocytes of diabetics is brought about by impaired glutathione synthesis and that the increase in the levels of glutathione disulfide is brought about by the decreased transport activity of glutathione disulfide through the erythrocyte membrane together with a decrease in the activity of glutathione reductase. These data also suggest that the impairment of glutathione metabolism weakens the defense mechanism against oxidative stress in erythrocytes of diabetics.
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PMID:Impairment of glutathione metabolism in erythrocytes from patients with diabetes mellitus. 256 61

The Escherichia coli structural gene for glutathione synthetase, gshB, was cloned into pBR322. Plasmids containing gshB were able to complement the glutathione requirement of a trxA gshB double mutant, and cells containing the plasmids were found to have elevated levels of glutathione synthetase. A mutant gshB allele was constructed by inserting the kan gene from pUC4K into a unique HpaI site located within gshB. The resulting plasmid-encoded allele was used to replace a genomic gshB+ by homologous recombination. The resulting strain had no detectable glutathione synthetase activity. The gshB allele containing the kan insertion was used to map gshB on the E. coli chromosome by P1 transduction. The results indicated that gshB is located at 63.4 min, between metK and speC. The allele was further localized to a region of 3,100 to 3,120 kilobase pairs on the physical map (restriction map) of E. coli by DNA-DNA hybridization to a series of lambda bacteriophages (Y. Kohara, K. Akiyama, and K. Isono, Cell 50:495-508, 1987).
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PMID:In vitro construction of gshB::kan in Escherichia coli and use of gshB::kan in mapping the gshB locus. 267 Sep 10

The glutathione synthetase from Escherichia coli B has been crystallized from 27% saturated ammonium sulfate solution (pH 5.5). The crystals are hexagonal, space group P6(2)22 or P6(4)22. The cell dimensions are a = b = 88.0 A, c = 164.2 A, and gamma = 120 degrees. The enzyme is a tetramer (Mr = 143,000) with 222 symmetry, and the asymmetric unit contains one subunit molecule (Mr = 35,600). The crystals diffract to at least 2.5 A resolution.
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PMID:Crystallization and preliminary X-ray studies of glutathione synthetase from Escherichia coli B. 268 23

Pyroglutamic acidemia, a rare metabolic disorder, usually appears in infancy. It is characterized by retardation, ataxia, hemolytic anemia, and chronic acidosis and is caused by a marked deficiency of glutathione synthetase (EC 6.3.2.3) activity. This disease is inherited as an autosomal recessive trait, but the clinical condition is also detected in heterozygotes. We report an unusual case of high-anion-gap metabolic acidosis in a 52-year-old woman who was admitted with neurological complaints and breathing problems but without the characteristic clinical features of congenital glutathione synthetase deficiency. The etiology of the acidosis could not be attributed to ketoacidosis, lactic acidosis, or ingestion of methanol, salicylate, or ethylene glycol. Analysis of the patient's plasma and urine for organic acids revealed the presence of high concentrations of pyroglutamate (5-oxoproline), which remained high throughout her hospitalization.
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PMID:Pyroglutamic acidemia in an adult patient. 229 27


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