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

The nucleotide sequence of the cloned DNA, 1,478 bp in length coding for glutathione synthetase (GSH-II) of E. coli B has been determined. Amino acid and nucleotide sequence analyses have assigned the open reading frame for GSH-II, starting with the ATG near its 5' terminus. The molecular weight calculated from the predicted amino acid sequence is 35,559 daltons, being in good agreement with that of a GSH-II subunit estimated by the SDS-PAGE method. Several signal sequences conserved in the promoter regions of E. coli were found in the non-coding regions of the gsh-II gene. They include the Shine-Dalgarno sequence, the Pribnow box and the sequence conserved in the "-35 region" with a preferable spacing from each other for an efficient transcription. Downstream from the termination codon, the inverted repeat sequences were present, followed by 6 successive T's. These structural features found in the non-coding regions have suggested to be involved in regulatory functions for the gsh-II gene expression.
 ...
PMID:Complete nucleotide sequence of the E. coli glutathione synthetase gsh-II. 639 55

A male newborn infant presented with metabolic acidosis and haemolytic anaemia. Renal tubular acidosis was suspected in the absence of amino aciduria and the patient was treated with sodium bicarbonate. Two years later, the chronic acidosis, clinical observation of developmental delay and ataxia prompted further investigational studies. 5-Oxoprolinuria was identified by gas-liquid chromatography and confirmed by mass spectrometry after an initial mass spectrum analysis reported a glutamic acid artifact. Glutathione and glutathione synthetase in erythrocytes were 25% and 5% of control values, respectively. On the basis of neonatal metabolic acidosis, without amino aciduria and an elevated reticulocyte count, a recommendation is made for blood glutathione and urine 5-oxoproline screening, followed by glutathione synthetase assay for confirmation of neonatal 5-oxoprolinuria.
 ...
PMID:Neonatal 5-oxoprolinuria: difficult-to-diagnose? 640 9

The activity of glutathione synthetase from bovine lens was examined as a functions of the concentration of L-gamma-glutamyl-L-alpha-aminobutyrate, the dipeptide substrate required in the formation of ophthalmic acid. Several significant anomalies of the glutathione synthetase-catalyzed formation of ophthalmic acid were found. Curvilinearity of double reciprocal plots occurred with this substrate; this curvilinearity shows substrate activation of the reaction which is likely a result of negative cooperativity. Both ATP4- and, to a lesser extent Mg2+ inhibited the reaction, whereas MgATP2- is the substrate; maximum activity occurred with 2 mM Mg2+ in excess of the concentration of added ATP. This investigation shows that it is necessary to establish a defined set of conditions for reporting enzyme activity and that the usual practice of using very large concentrations of Mg2+ relative to ATP, and 5- to 20-fold excess of the dipeptide will give less than optimum activity. The unit of enzyme activity is suggested to be that activity in ml using 2 mM ATP, 4 mM Mg2+, 30 mM glycine and 15 mM L-gamma-glutamyl-alpha-aminobutyrate, which results in the formation of 1 nmole/minute of ADP or P(i). In this study, 5'-AMP was for the first time, shown to be an inhibitor of the reaction with a K(i) of 0.9 mM.
 ...
PMID:Glutathathione synthetase of bovine lens: anomalies of the enzyme-catalyzed formation of ophthalmic acid. 654 96

Cultured skin fibroblasts from patients with 5-oxoprolinuria caused by hereditary deficiency of glutathione synthetase have decreased levels of the corresponding enzyme as well as of glutathione. Fibroblasts from the same patients accumulated gamma-glutamyl cysteine, but the levels were lower than those of glutathione in control fibroblasts. The uptake of [35S]cystine was equally rapid in control and patient fibroblasts. In the acid-soluble fraction gamma-glutamyl-[35S]cysteine accumulated in fibroblasts from patients but not from controls. Appreciable turnover of gamma-glutamyl cysteine and glutathione in the respective cell strains was observed, the half-lives of these pools being approximately 5 hours. The growth rate of mutant fibroblasts in culture was significantly slower than that of control fibroblasts. There was no significant accumulation of 5-oxoproline in the culture medium.
 ...
PMID:Glutathione synthetase deficient human fibroblasts in culture. 665 19

An experimental approach to the pharmacogenetics of human idiosyncratic drug reactions requires an assay for determining individual differences in susceptibility that does not expose patients to further drug-related risk. We have developed an in vitro drug toxicity assay designed to test the hypothesis that differences in susceptibility may be based on genetic abnormalities in the detoxification of electrophilic drug metabolites. Lymphocytes are challenged with metabolites generated by a murine hepatic microsomal system. By using cells from patients deficient in glutathione synthetase, we found that cells with decreased glutathione defenses are more sensitive to toxicity from metabolites of drugs such as acetaminophen, nitrofurantoin, and metronidazole. The assay was then applied to studying the pharmacogenetics of phenytoin hepatotoxicity. We found an inherited defect in the detoxification of phenytoin arene oxide metabolites in cells from patients and their relatives. The studies have led to an elucidation of a genetically heterogeneous group of detoxification defects for arene oxide metabolites of various aromatic drugs. Such experimental approaches may be useful in diagnosing idiosyncratic drug reactions, in establishing their pharmacogenetic basis, and perhaps in predicting toxicity potential of drugs for selected patients and families.
 ...
PMID:In vitro assessment of pharmacogenetic susceptibility to toxic drug metabolites in humans. 671 38

The frequency of X-ray-induced DNA breaks was determined in human cell lines which are deficient in glutathione synthetase and have a greatly reduced glutathione content. Hydroxyapatite chromatography was used for the estimation of the DNA breaks in cell cultures, which were derived either from lymphoblasts transformed by infection with EB virus or from fibroblasts. The dose-effect relationship for the induction of breaks when radiation exposure was made in argon, was similar to that found when exposure was made in air. In control cultures with normal glutathione content, the induction of breaks was enhanced when irradiation was made under aerobic, instead of anaerobic, conditions. Treatment of the glutathione-deficient cells with the hypoxic radiosensitizer misonidazole did not enhance the induction of breaks by radiation delivered either in air or in argon. In control cultures, radiation induction of breaks was enhanced by misonidazole under anaerobic but not under aerobic conditions. When the glutathione-deficient cells were pretreated with cysteamine however, irradiation in the absence of oxygen resulted in a decreased frequency of DNA breaks.
 ...
PMID:Lack of oxygen effect in glutathione-deficient human cells in culture. 696 72

Using the unwinding technique in weak alkali, the induction and repair of DNA single-strand breaks was determined after aerobic and anerobic X-irradiation of human fibroblasts, obtained from a patient suffering from 5-oxoprolinuria, and from a clinically healthy control. The metabolic disorder associated with 5-oxprolinuria is a deficiency in glutathione synthetase activity resulting in a greatly reduced glutathione content in the cells. A small dose-modifying effect of oxygen (o.e.r. = 1.1) was found for these cells in comparison to an o.e.r. of 2.5 for control cells with normal glutathione content. No significant difference was found between the repair capacity of cells with normal and deficient glutathione content, and repair was nearly completed within 60 min of anoxic irradiation in each case. In contrast, after aerobic irradiation of glutathione-deficient cells repaired less than 70 per cent of the breaks during the same period. When the glutathione-deficient cells were incubated with either dithiothreitol or mercaptopropionylglycine directly after aerobic irradiation, almost complete repair was obtained within 60 Min. The data are interpreted as indicating that the repair mechanism for oxically and anoxically induced single-strand breaks is qualitatively different, and requires glutathione in the former case.
 ...
PMID:Induction and repair of single-strand DNA breaks after X-irradiation of human fibroblasts deficient in glutathione. 697 50

Important insights have recently been derived from studies of inborn human defects of sulfur metabolism. Metabolic lesions responsible for homocystinuria have been elucidated, with possible implications for understanding atherogenesis in the general population. The cause of cystinosis remains enigmatic, but important information has been gained on the origin of some stored cystine from degraded protein. Cysteamine and ascorbic acid deplete the cystine content of cystinotic fibroblasts in vitro, and clinical trials with these agents have been undertaken. Studies of patients with glutathione synthetase deficiency have provided new understanding of the roles of glutathione as in antioxidant and as a modulator of microtubule-related processes. Studies of patients with this disorder and glucose-6-phosphate dehydrogenase deficiency, in which the capacity to maintain glutathione in the reduced state is compromised, indicate that pharmacologic doses of vitamin E can correct certain functional consequences of an inadequate supply of reduced glutathione both in erythrocytes and polymorphonuclear leukocytes. Much remains to be learned about the mechanisms of membrane damage in these states of enhanced oxidative susceptibility.
 ...
PMID:Genetic disorders of glutathione and sulfur amino-acid metabolism. New biochemical insights and therapeutic approaches. 699 53

A methylglyoxal-resistant mutant of Escherichia coli B excreted glutathione into the growth medium, especially during growth on medium containing methylglyoxal. In the presence of methylglyoxal, the total amount of glutathione excreted was increased about 50-fold over that of the wild-type strain. The resistant mutant had high activities of two enzyme systems: a glutathione-forming enzyme system (consisting of gamma-glutamylcysteine synthetase and glutathione synthetase) and a glyoxalase system (consisting of glyoxalase I and glyoxalase II). Methylglyoxal resistance appeared to be due to the simultaneous increase in the activities of these two enzyme systems.
 ...
PMID:Excretion of glutathione by methylglyoxal-resistant Escherichia coli. 701 75

1H, 2H and 15N n.m.r. spectroscopy was used to monitor the incorporation of free glycine into the glycine residue of reduced glutathione (GSH) in suspensions of intact human erythrocytes. The following results were obtained. (i) By using 1H spin-echo n.m.r. the exchange reaction between [2H5]glycine and the protonated glycine residue of GSH was studied at various [2H5]glycine concentrations, thus enabling the calculation of an apparent Michaelis constant (Km) and maximal velocity (Vmax.) for the process. (ii) The reaction is catalysed by glutathione synthetase and proceeds most rapidly in the absence of glucose, which is the main physiological energy source of the erythrocyte. (iii) 15N n.m.r. spectroscopy, with a one-pulse sequence, and 2H n.m.r. spectroscopy, with an inversion recovery method, enabled demonstration of the incorporation of labelled glycine into an intra-erythrocyte peptide, consistent with incorporation into GSH. (iv) The exchange reaction, although inhibited by glucose, appeared not to be dependent on low ATP or 2,3-bisphosphoglycerate concentrations.
 ...
PMID:Incorporation of labelled glycine into reduced glutathione of intact human erythrocytes by enzyme-catalysed exchange. A nuclear-magnetic-resonance study. 718 63


<< Previous 1 2 3 4 5 6 7 8 9 10