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At least 19 recordsLinked to original sources
PubMed1976

Cell potentials, cell resistance, and proton fluxes in corn root tissue: effects of dithioerythritol.

Studies were made of the effect of dithioerythritol on net proton flux, potassium influx and efflux, cell potential, and cell resistance in fresh and washed corn (Zea mays L. WF9XM14) root tissue. Dithioerythritol induces equal proton influx and potassium efflux rates, decreases membrane resistance, and hyperpolarizes the cell potential. Greater effects on H(+) and K(+) fluxes are secured at pH 7 than at pH 5. Other sulfhydryl-protecting reagents produced the same responses. No evidence could be found that dithioerythritol affected energy metabolism or membrane ATPase, and proton influx was induced in the presence of uncoupling agents.We deduce that dithioerythritol activates a passive H(+)/K(+) antiport, driven in these experiments by the outwardly directed electrochemical gradient of K(+). The net effect on H(+) and K(+) fluxes is believed to reside with the combined activity of a polarized H(+)/K(+) exchanging ATPase and the passive H(+)/K(+) antiport. A model is presented to show how the combined system might produce stable potential differences and K(+) content.

Journal Article↗
PubMed1984

Hepatic uptake of cadmium and its biliary release as affected by dithioerythritol and glutathione.

Net cadmium uptake in the isolated perfused rat liver was half-maximal at 5 microM, and the maximal rate of uptake was 22 nmoles/min per gram liver wet weight. Uptake was augmented when a permeable thiol, dithioerythritol, was infused, whereas it was restricted when glutathione as a nonpermeable thiol or also when bovine serum albumin were infused. The ratio of extra cadmium taken up versus dithioerythritol added was 1:2. Uptake of cadmium was insensitive to anoxia or to the infusion of cyanide. Biliary cadmium release in the perfused liver was not augmented by dithioerythritol but was rather suppressed, whereas bile flow or the release of added 3H-taurocholate were unaffected.

Animals↗
PubMed1978

The presence of two (Na+ + K+)-ATPase inhibitors in equine muscle ATP: vanadate nad a dithioerythritol-dependent inhibitor.

A potent inhibitor of (Na+ + K+)-ATPase activity was purified from Sigma equine muscle ATP by cation- and anion-exchange chromatography. The isolated inhibitor was identified by atomic absorption spectroscopy and proton resonance spectroscopy to be an inorganic vanadate. The isolated vanadate and a solution of V2O5 inhibit sarcolemma (Na+ + K+)-ATPase with an I50 of 1 micrometer in the presence of 1 mM ethyleneglycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA), 145 mM NaCl, 6mM MgCl2, 15 mM KCl and 2 mM synthetic ATP. The potency of the isolated vanadate is increased by free Mg2+. The inhibition is half maximally reversed by 250 micrometer epinephrine. Equine muscle ATP was also found to contain a second (Na+ + K+)-ATPase inhibitor which depends on the sulfhydryl-reducing agent dithioerythritol for inhibition. This unknown inhibitor does not depend on free Mg2+ and is half maximally reversed by 2 micrometer epinephrine. Prolonged storage or freeze-thawing of enzyme preparations decreases the susceptibility of the (Na+ + K+)-ATPase to this inhibitor. The adrenergic blocking agents, propranolol and phentolamine, do not block the catecholamine reactivation. The inhibitors in equine muscle ATP also inhibit highly purified (Na+ + K+)-ATPase from shark rectal gland and eel electroplax. The inhibitors in equine muscle ATP have no effect on the other sarcolemmal ATPases, Mg2+-ATPase, Ca2+-ATPase and (Ca2+ + Mg2+)-ATPase.

Adenosine Triphosphatases↗
PubMed1985

Effects of dithiothreitol, dithioerythritol and chelating agents on 5'-nucleotidase from bull seminal plasma.

5'-Nucleotidase from bull seminal plasma is inhibited by dithiothreitol and dithioerythritol. These reactives proved to dissociate the dimeric glycoprotein 5'-nucleotidase of Mr 160 000 into two subunits of apparent Mr 80 000, indicating that the subunits are held together by interchain disulfide bridges. HPLC determinations of cysteic acid and carboxymethylcysteine protein derivatives resulted in 50 +/- 3 half-cystine plus cysteine residues, while 1.9 +/- 0.4 free cysteine residues were estimated by HPLC analysis. The enzyme is inhibited by EDTA and EGTA, and the inhibition appears to be of the non-competitive type for both the chelating agents. Experiments for the enzyme activity recovery by MgCl2 and CaCl2 additions, after the EDTA and EGTA treatments in the presence of 8 M urea, are reported.

5'-Nucleotidase↗
PubMed2003

Dithioerythritol (DTE) prevents inhibitory effects of triphenyltin (TPT) on the key enzymes of the human sex steroid hormone metabolism.

Organotins are known to induce imposex (pseudohermaphroditism) in marine neogastropods and are suggested to act as specific endocrine disruptors, inhibiting the enzyme-mediated conversion of steroid hormones. Therefore, we investigated the in vitro effects of triphenyltin (TPT) on human 5alpha-reductase type 2 (5alpha-Re 2), cytochrome P450 aromatase (P450arom), 17beta-hydroxysteroid dehydrogenase type 3 (17beta-HSD 3), 3beta-HSD type 2 and 17beta-HSD type 1 activity. First, the present study demonstrates that significant amounts of TPT occurred in the blood of eight human volunteers (0.17-0.67 microg organotin cation/l, i.e. 0.49-1.92 nmolcation/l). Second, TPT showed variable inhibitory effects on all the enzymes investigated. The mean IC(50) values were 0.95 microM for 5alpha-Re 2 (mean of n=4 experiments), 1.5 microM for P450arom (n=5), 4.0 microM for 3beta-HSD 2 (n=1), 4.2 microM for 17beta-HSD 3 (n=3) and 10.5 microM for 17beta-HSD 1 (n=3). To exclude the possibility that the impacts of TPT are mediated by oxidizing essential thiol residues of the enzymes, the putative compensatory effects of the reducing agent dithioerythritol (DTE) were investigated. Co-incubation with DTE (n=3) resulted in dose-response prevention of the inhibitory effects of 100 microM deleterious TPT concentrations on 17beta-HSD 3 (EC(50) value of 12.9 mM; mean of n=3 experiments), 3beta-HSD 2 (0.90 mM; n=3), P450 arom (0.91 mM; n=3) and 17beta-HSD 1 (0.21 mM; n=3) activity. With these enzymes, the use of 10mM DTE resulted in an at least 80% antagonistic effect, whereas, the effect of TPT on 5alpha-Re 2 was not compensated. In conclusion, the present study shows that TPT acts as an unspecific, but significant inhibitor of human sex steroid hormone metabolism and suggests that the inhibitory effects are mediated by the interaction of TPT with critical cysteine residues of the enzymes.

17-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

2,3-Dithioerythritol, a possible new arsenic antidote.

British antilewisite (2,3-dimercaptopropanol; BAL) has long been used as an arsenic antidote, but its therapeutic efficacy is limited by its inherent toxicity. We synthesized two less toxic derivatives of BAL and investigated their potential as antidotes to organic arsenic. The new compounds, 2,3-dithioerythritol (DTE) and 2,2-dimethyl-4-(hydroxymethyl)-1,3-dithiolane (isopropylidene derivative of BAL), react readily with phenyldichloroarsine (PDA) to yield the expected corresponding cyclic 1,3-dithioarsolanes. The BAL derivatives were compared to BAL in terms of their cytotoxicity and their ability to rescue PDA-poisoned mouse lymphoma cells in culture. The dithiolane was not a good antidote in the cultured cell system. In contrast, DTE was less toxic than BAL or DMSA and was superior at improving cell survival in PDA-exposed cells.

Animals↗
PubMed1989

Successful renal allografts in recipients with crossmatch-positive, dithioerythritol-treated negative sera. Race, transplant history, and HLA-DR1 phenotype.

Graft survival was examined in 15 renal allograft recipients from a group of 20 patients with IgM autolymphocytotoxic antibody that could be removed in a crossmatch assay using a reducing agent, dithioerythritol (DTE). The significant differences in this group of 20 patients compared with end-stage renal disease (ESRD) patients lacking autolymphocytotoxic antibodies included an increased frequency of black patients (P = 0.002), a lack of previous transplants (P = 0.003), and an increased frequency of the HLA-DR1 phenotype (P = 0.0001). Sex and the number of transfusions did not appear significant, whereas the cause of ESRD was primarily systemic lupus erythematosus. Fifteen of the 20 patients were transplanted against a positive donor crossmatch. Eleven were recipients of cadaveric kidneys, nine of which are still functioning for periods ranging from 0.5 to 40 months. Two fo the cadaveric recipients died with functional grafts. Four received living-related donor transplants, one of which was lost to acute rejection one month posttransplant, while the remaining three have survived 1.5, 9, and 21 months, respectively. Fourteen patients had immediate allograft function with no hyperacute rejection and only one case of acute tubular necrosis (ATN) was found. In summary, a negative crossmatch using DTE-treated, autologous reactive recipient sera may identify a group of patients who can be transplanted with minimal concern for hyperacute rejection or ATN. In addition to cause of ESRD, race, transplant history, and HLA-DR phenotype may further define this group of transplant candidates having IgM autolymphocytotoxic antibody. Extrapolation of these conclusions to transplant candidates lacking autolymphocytotoxic antibodies is not warranted.

Absorption↗
PubMedDate not supplied

Chlorpromazine and dithioerythritol protection against acute ethanol toxicity.

Our previous work has shown that an increase in body temperature increases the acute toxicity of ethanol in mice. To determine whether a decrease in body temperature would have the opposite effect, we studied the effect of two substances that decrease body temperature (chlorpromazine (CPZ) and dithioerythritol (DE)) on ethanol toxicity. Matched groups of 10 mice were injected sc with CPZ (5 mg/kg), DTE (80 mg/kg), or saline (controls). CPZ and DTE significantly depressed the rectal temperature to 32.8 and 34.5 degrees C, respectively. One hour later, all three groups received a specified dose of ethanol (6.5-10.7 g/kg, 24% w/v, intraperitoneal). The experiment was repeated 17 times at different ethanol doses. The pretreatments increased the 1 hr LD50 from 7.8 +/- 0.1 g/kg for the controls to 8.6 +/- 0.2 g/kg (DTE) and 10.0 +/- 0.3 g/kg (CPZ) (p less than 0.001). The protective effect of CPZ was maximal around 5 mg/kg, and less at both lower and higher CPZ doses. When the temperature drop was prevented by directly heating the mice, the protective effect of DTE could be eliminated, but the effect of CPZ was only partially prevented. Placing the CPZ-treated mice in a warmer environment only produced a major reversal of CPZ protection when rectal temperature reached 38 degrees C. In conclusion, CPZ and DTE both decrease body temperature and protect against acute ethanol toxicity. The protection seems to be due at least partially to the decrease in body temperature prior to ethanol injection.

Animals↗
PubMed1975

Effects of various protein-modifying agents and the aminonucleoside of puromycin on dithioerythritol-reducible disulfide in glomerular basement membrane.

Comparative study of dithioerythritol-reducible (DTE) disulfide bonds in glomerular basement membranes (GBM) isolated from normal rats and from similar groups of rats treated with the nephrosis-producing aminonucleoside of puromycin emphasize not only the importance of such linkages in the interaction and structural organization of the macromolecular GBM collagen-glycoprotein matrix but also suggest a modality by which GBM semi-permeability might be engendered. Although DTE-reducible disulfide is significantly reduced in GBM of rats as early as the fourth day after administration of a nephrosis-producing dose of the aminonucleoside it has not been possible to demonstrate an unequivocal in vitro or direct effect of the drug on DTE-reducible disulfide in normal GBM. Several-fold increases in DTE-reducible disulfide in GBM subjected to the denaturing action of guanidine-HCl or the proteolytic action of pronase indicates that most of the disulfide lies buried in the GBM. Location of disulfide crosslinks in the innermost regions or core of the GBM might be expected to not only stabilize the membrane but also to protect the GBM from a considerable array of disulfide cleaving (reductases) within the kidney cortex.

Animals↗
PubMed1984

Inhibition by dithioerythritol of alloxan induced efflux of Ca2+ and accompanying alterations in isolated liver mitochondria.

Isolated mouse liver mitochondria respiring on succinate released Ca2+ when incubated with alloxan, accompanied by decreased membrane potential, stimulated state 4 respiration and swelling. All these effects of alloxan were inhibited by equimolar or higher concentrations of dithioerythritol (DTE), and in presence of added ATP a carboxyatractyloside-sensitive reuptake of Ca2+ was observed. The process of release and uptake of Ca2+ could be repeated by additional administrations of higher concentrations of alloxan and DTE plus ATP, respectively. The data suggest that the mitochondrial action of alloxan involves oxidation of membrane thiol groups.

Alloxan↗
PubMed1979

Activation of fungal alpha-amylase by dithioerythritol.

The activity of fungal alpha-amylase has been shown to be influenced by disulfide-reducing reagents. Thus, the enzymatic activity increases in the presence of dithioerythritol or 2-mercaptoethanol. L-Cysteine is also capable of increasing the activity, but the activation competes with an inactivation reaction which dominates at higher reagent concentrations (greater than 20 mM). A possible scheme interpreting the results is given.

Amylases↗
PubMed1979

Improved identification of antitrypsin phenotypes through isoelectric focusing with dithioerythritol.

Isoelectric focusing has replaced acid starch-gel electrophoresis for the routine determination of antitrypsin phenotypes in recent years. We observed increased sharpness of antitrypsin bands and decreased background stain following the addition of DTE to serum before isoelectric ofcusing in polyacrylamide gels. DTE and DTT were the only sulfhydryl reducing agents which produced this effect. Electrophoretic mobility of antitrypsin bands was increased very slightly. Decreased background stain resulted from the precipitation of albumin. Precipitation (coagulation) of albumin was complete in serum after 60 min incubation at 37 degrees C at concentrations of 30 mM DTE or DTT. Optimal pH for denaturation was 7.6 to 8.8. Ionic concentrations reduced the strength of the coagulum at 2.5M sodium chloride but had little effect at lower concentrations. Marked temperature effects were noted. As a result of these studies, we recommend examination of native and reduced (30 mM DTE) serum on isoelectric focusing in polyacrylamide gel for all samples submitted for routine antitrypsin phenotype determinations. It also seems possible that the nontoxic DTE (DTT) precipitation of albumin could prove useful for studies of serum proteins other than alpha 1-antitrypsin.

Animals↗