Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1260386 (GSH)
 38,102 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human plasma glutathione peroxidase (GSH-Px) is a distinct extracellular selenoenzyme that detoxifies hydroperoxides when used with GSH in high (mM) non-physiological concentrations. We have discovered that NADPH and human thioredoxin reductase (TR) by itself or with thioredoxin (Trx) are efficient electron donors to this human plasma peroxidase. Incubation of 0.05 microM TR with 0.25 microM GSH-Px, in a system free from GSH, resulted in reduction of t-butyl hydroperoxide. Addition of Trx, 2.5 and 5 microM, respectively, further increased the rate of the reaction. These data were obtained using an assay measuring the oxidation of NADPH. A direct assay demonstrated the formation of cumyl alcohol from cumene hydroperoxide in this GSH-independent peroxidase reaction. Incubation of 0.25 microM GSH-Px with a low concentration of GSH (10 microM), representing the upper level in plasma, plus excess glutathione reductase and NADPH did not result in any reduction of t-butyl hydroperoxide. However, after addition of 2.5 microM human glutaredoxin, a linear peroxidase reaction started. The results suggest that extracellular TR, Trx, or glutaredoxin are reductants for the selenium-dependent peroxidase rather than GSH.
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PMID:The thioredoxin and glutaredoxin systems are efficient electron donors to human plasma glutathione peroxidase. 796 15

Chloroplast NADP-malate dehydrogenase (NADP-MDH) from pea and from spinach was N-terminally truncated by limited proteolysis with Staphylococcus aureus protease V8. The resulting monomeric enzymes lacking, respectively, the 37 and 38 N-terminal amino acids were inactive. Reduction and addition of low concentrations of guanidine-HCl (50-100 mM) resulted in a highly active enzyme of 850 units per mg protein. Equilibration of the truncated enzyme with various glutathione (GSH) redox buffers and assaying its activity in the presence of guanidine-HCl was used to establish the existence of protein-GSH mixed disulfides. This finding was further confirmed using incorporation of radioactively labelled thiol. The possible function of such cysteine modifications under oxidative stress and their regeneration by the thioredoxin system in the light is discussed.
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PMID:Cysteines of chloroplast NADP-malate dehydrogenase form mixed disulfides. 798 83

The thioredoxin/thioredoxin reductase system is important for several aspects of the regulation of cellular proliferation by both intracellular and extracellular mechanisms. The effects of n-butyl 2-imidazolyl disulfide (III-2), 1-methylpropyl 2-imidazolyl disulfide (IV-2), and n-decyl 2-imidazolyl disulfide (VII-2) on purified human placental thioredoxin reductase activity were examined. The analogues were competitive inhibitors with DTNB for reduction by thioredoxin reductase, with Ki values for III-2, IV-2, and VII-2 being 3.3, 13.0, and 8.6 microM, respectively. The inhibition was noncompetitive with reduced nicotinamide adenine dinucleotide phosphate (NADPH). None of the analogues was a suicide substrate inhibitor of the flavoenzyme. III-2 and VII-2 were metabolized by thioredoxin reductase at about half the rate of DTNB, whereas IV-2 was not detectably metabolized. The second order rate constants for the reactions of III-2 and IV-2 with reduced GSH were 931 and 91 M-1 s-1, respectively. The lower reactivity of IV-2 with reduced GSH and the lack of the analogue's metabolism by thioredoxin reductase may be due to the more sterically hindered structure of this analogue. The 50% inhibitory concentrations (IC50 values) for the inhibition of serum-dependent cellular proliferation of Swiss 3T3 murine fibroblasts by III-2, IV-2, and VII-2 were 2.0, 3.5, and 4.0 microM, respectively. IV-2 was considerably more potent as an inhibitor of the thioredoxin-dependent cellular proliferation of Swiss 3T3 fibroblasts, showing an IC50 value of 60 nM. Thus, inhibition of cellular proliferation by alkyl 2-imidazolyl disulfide analogues may involve interaction with thioredoxin, thioredoxin reductase, or an alternative target that is redox-regulated by thioredoxin.
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PMID:Reversible inhibition of human thioredoxin reductase activity by cytotoxic alkyl 2-imidazolyl disulfide analogues. 807 12

This work investigates whether a mutator phenotype is associated to the simultaneous deficiency in thioredoxin and glutaredoxin, the two known hydrogen donors of ribonucleotide reductase. To this end, new Escherichia coli K-12 strains carrying delta trxA and/or grx::kan null mutations were constructed to monitor mutagenesis by selecting forward mutations to L-arabinose resistance. Highly sensitive and specific enzyme-linked immunoassays were developed to confirm that trx-grx- cells lacked thioredoxin and glutaredoxin. A number of remarkable properties were observed in the newly constructed thioredoxin- and glutaredoxin-deficient bacteria compared with the wild type cells. Thus, they (i) grew on minimal medium plates, suggesting that the presence of thioredoxin and glutaredoxin may not be absolutely essential for sulfate reduction; (ii) showed normal mutagenic sensitivities toward a wide variety of DNA-damaging agents, as compared with wild type cells and trx- or grx- single mutants; (iii) displayed 14% of GSH-dependent and 30% of NADPH-dependent ribonucleotide reduction capacity with CDP as substrate in the presence or the absence of exogenous ribonucleotide reductase, respectively; and (iv) showed very high levels of ribonucleotide reductase activity, which was increased from 19- to 23-fold. The existence of a new glutathione-dependent hydrogen donor for ribonucleotide reductase and the high activity levels of this enzyme in trx-grx- defective cells could explain that thioredoxin and the first discovered glutaredoxin are not essential for deoxyribonucleotide synthesis, even under mutagenic stress.
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PMID:Null thioredoxin and glutaredoxin Escherichia coli K-12 mutants have no enhanced sensitivity to mutagens due to a new GSH-dependent hydrogen donor and high increases in ribonucleotide reductase activity. 820 82

The proliferative response of PBMC to PHA, Con A, OKT3 mAb and IL-2-dependent proliferation of PHA-blasts was examined in a thiol-free environment (cultured in a L-cystine- and GSH-free medium). [3H]TdR incorporation assay and cell cycle analysis revealed that stimulated PBMC could not enter the S phase when deprived of these thiol compounds. In thiol-free cultures, an increase in intracellular free Ca2+ concentration and IL-2R alpha-chain/p 55 (Tac) induction was still observed, whereas transferrin receptor induction was markedly reduced, suggesting that the proliferative response of mitogenically stimulated PBMC was arrested in the late G1 phase in which transferrin receptor is induced. In GSH-depleted cultures, a similar reduction of the proliferative response of PBMC and PHA-blasts was observed when the concentration of L-cystine was lowered, in a dose-dependent manner. Each reduction or loss of proliferative response was partially restored by supplementation of 2-ME or adult T cell leukemia-derived factor (ADF)/human thioredoxin which is considered to be an endogenous dithiol-reducing factor. L-Cystine transport analysis showed that mitogenically stimulated PBMC and PHA blasts incorporated L-cystine, whereas resting PBMC did not. Furthermore, ADF as well as 2-ME exhibited an enhancing activity on the L-cystine transport in PHA blasts. Together with the fact that L-cystine transport is a limiting step in glutathione synthesis, these findings suggest that GSH and ADF might cooperate in the thiol-mediated redox regulation process and might also play key roles in cell cycle (late G1 to S) progression of activated lymphocytes.
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PMID:Thiol-mediated redox regulation of lymphocyte proliferation. Possible involvement of adult T cell leukemia-derived factor and glutathione in transferrin receptor expression. 820 97

The primary and secondary structure of glutaredoxin-3 (Grx3), a glutathione-disulfide oxidoreductase from Escherichia coli, has been determined. The amino acid sequence of Grx3 consists of 82 residues and contains a redox-active motif, Cys-Pro-Tyr-Cys, typical of the glutaredoxin family. Sequence comparison reveals a homology (33% identity) to that of glutaredoxin-1 (Grx1) from E. coli as well as to other members of the thioredoxin superfamily. In addition to the active site cysteine residues, Grx3 contains one additional cysteine (Cys65) corresponding to one of the two non-active site (or structural) cysteine residues present in mammalian glutaredoxins. The sequence-specific 1H and 15N nuclear magnetic resonance assignments of reduced Grx3 have been obtained. From a combined analysis of chemical shifts, 3JHNalpha coupling constants, sequential and medium range NOEs, and amide proton exchange rates, the secondary structure of reduced Grx3 was determined and found to be very similar to that inferred from amino acid sequence comparison to homologous proteins. The consequences of the proposed structural similarity to Grx1 are that Grx3, while possessing a largely intact GSH binding cleft, would have a very different spatial distribution of charged residues, most notably surrounding the active site cysteine residues and occurring in the proposed hydrophobic protein-protein interaction area. These differences may contribute to the observed very low Kcat of Grx3 as a reductant of insulin disulfides or as a hydrogen donor for ribonucleotide reductase. Thus, despite an identical active site disulfide motif and a similar secondary structure and tertiary fold, Grx3 and Grx1 display large functional differences in in vitro protein disulfide oxido-reduction reactions.
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PMID:Glutaredoxin-3 from Escherichia coli. Amino acid sequence, 1H AND 15N NMR assignments, and structural analysis. 863 94

The dithiol forms of thioredoxin and glutaredoxin are hydrogen donors for ribonucleotide reductase. We have determined the intracellular levels of ribonucleotide reductase (RRase), thioredoxin (Trx), glutaredoxin 1 (Grx1), and glutathione (GSH) and the glutathione redox status in new Escherichia coli K12 strains lacking thioredoxin (trxA-), glutaredoxin 1 (grxA-), and/or GSH (gshA-) or overproducing Trx or Grx1 from multicopy plasmids. We propose a regulatory network in which RRase levels are balanced with those of Trx, Grx1, and GSH so that deficiency or overproduction of one component would promote the opposite effect on the others to maintain a balanced supply of deoxyribonucleotides. GSH deficiency strongly increased both Grx1 levels and RRase activity, even more than Trx deficiency. Double gshA-trxA- bacteria were viable, whereas additional deficiency in lipoate synthesis (gshA-trxA-lipA-) caused the inability to grow in minimal medium plates supplemented with acetate plus succinate instead of lipoic acid. Thus, lipoate might be the only substitute of GSH for glutaredoxin reduction in gshA-trxA- cells, although the extremely high Grx1 content (55-fold) of these bacteria suggests that electron transfer from lipoate might be an inefficient reduction mechanism of glutaredoxins. Moreover, the enhanced Grx1 level of gshA-trxA- cells could obviate the need for a large increase in RRase activity, in contrast to grxA-trxA- double mutant cells. Impairment of the sulfate assimilation pathway, leading to very low GSH concentrations, and an oxidized glutathione redox state might explain the inability of grxA-trxA- cells to grow in minimal medium. Restoration of nearly normal levels of both GSH content and redox status cure the growth defect.
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PMID:The levels of ribonucleotide reductase, thioredoxin, glutaredoxin 1, and GSH are balanced in Escherichia coli K12. 870 83

In activated human neutrophils a burst of nitric oxide (NO) converts intracellular GSH to S-nitrosoglutathione (GSNO) which is subsequently cleaved to restore GSH by an unknown mechanism. We discovered that GSNO is an NADPH oxidizing substrate for human or calf thymus thioredoxin reductase (TR) with an apparent Km value of 60 microM and a Kcat of 0.6 x s-1. Addition of human thioredoxin (Trx) stimulated the initial NADPH oxidation rate severalfold but was accompanied by progressive inactivation of TR. Escherichia coli TR lacked activity with GSNO, but with E. coli Trx present, GSNO was reduced without inhibition of the enzyme. Chemically reduced E. coli Trx-(SH)2 was oxidized to Trx-S2 by GSNO with a rate constant of 760 M-1s-1 (7-fold faster than by GSSG) as measured by tryptophan fluorescence. Analysis of this reaction in the presence of oxymyoglobin revealed quantitative formation of metmyoglobin indicative of NO. release. Analysis of GSNO reduction demonstrated that oxidation of NADPH produced a stoichiometric amount of free GSH. These results demonstrate a homolytic cleavage mechanism of GSNO, giving rise to GSH and NO.. GSNO efficiently inhibited the protein disulfide reductase activity of the complete human or calf thymus thioredoxin systems. Our results demonstrate enzymatic cleavage of GSNO by TR or Trx and suggest novel mechanisms for redox signaling.
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PMID:S-nitrosoglutathione is cleaved by the thioredoxin system with liberation of glutathione and redox regulating nitric oxide. 870 96

Thioltransferase (TTase) activity was identified and partially purified from the ocular tissue for the first time. The enzyme activity depended on the presence of reduced glutathione (GSH), glutathione reductase (GR) and NADPH to reduce the disulfide bond in a synthetic substrate, hydroxyl ethyl disulfide (HEDS). Maximum activity was obtained in a pH 7.4 phosphate buffer at 30 degrees C. This enzyme distinguishes from other reducing enzymes such as thioredoxin that do not require GSH and GR for their catalytic activity. It also differs from the 52 kDa enzyme, protein disulfide isomerase by its smaller molecular size and its stability against heat treatment. TTase activity was higher in the epithelial layer but distributed evenly in the rest of the lens also, TTase showed similar activity in the lenses obtained from rats, pigs, bovine, guinea pigs, chick embryos and humans. The molecular weight of this enzyme was estimated to be 11.5 kDa on a SDS-PAGE system. Western blot analysis showed the protein reacted positively to the antibody raised by the purified pig liver TTase. Similarly the antibody raised by the partially purified lens enzyme reacted positively with the purified pig lever TTase. The presence of TTase in the lens was confirmed further with the slot blot analysis where it demonstrated a 32P-labeled cDNA from pig liver TTase hybridizing with the RNA in the pig lens or rabbit lens epithelium cells. Based on the above information it was concluded that the lens TTase is comparable to TTase from other tissues in its functional and structural properties. It is hypothesized that the lens TTase has a significant physiological role in sulfhydryl homeostasis in the lens by protecting the SH groups of the proteins from S-thiolation. It is speculated that, lens TTase may be primary antioxidant in the lens along with GSH and GR by protecting the vulnerable lens proteins against oxidative damage.
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PMID:Evidence for the presence of thioltransferase in the lens. 894 50

In rheumatoid arthritis (RA), T cells isolated from the synovial fluid (SF) show impaired responses to mitogenic stimulation compared with T cells from the peripheral blood (PB). Here it is reported that hyporesponsiveness of SF T cells correlated with a significant decrease in the levels of the intracellular redox-regulating agent glutathione (GSH). GSH was decreased in both CD4+ (p = 0.0022) and CD8+ (p = 0.0010) SF T cell subsets compared with PB CD4+ and CD8+ T cells in RA patients. Levels of thioredoxin (TRX), another key redox mediator, previously found to be secreted under conditions of oxidative stress, were found to be significantly increased in SF compared with plasma samples of RA patients (p = 0.005). Increased levels of TRX in the SF of inflamed joints was found to be associated with RA when compared with other arthritides (p = 0.007). Restoration of GSH levels in SF T cells with N-acetyl-L-cysteine (NAC), enhanced mitogenic induced proliferative responses and IL-2 production. Collectively, these data impute an important role to an altered redox state in the hyporesponsiveness of joint T cells in patients with RA.
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PMID:Evidence for the role of an altered redox state in hyporesponsiveness of synovial T cells in rheumatoid arthritis. 901 92


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