Glutathione regeneration in calcium-loaded erythrocytes: a possible relationship among calcium accumulation,ATP decrement and oxidative damage

Glutathione (GSH) regeneration was studied in rabbit erythrocytes which were loaded with calcium using ionophore A23187. Calcium-loading induced by A23187 and various concentrations of CaCl₂ caused a dose-dependent depression in red cell GSH regeneration. The lowered GSH regeneration was mainly due to reduction of ATP level. In an experiment using haemolysate, the effect of calcium per se was negligible, while magnesium strongly affected GSH regeneration by controlling the rate of hexokinase reaction. These results indicate a possibility that cation perturbation, metabolic decay and oxidative damage are all interrelated in the erythrocyte aging process.     

Erythrocyte biochemistry of the grey-headed fruit bat (Pteropus poliocephalus)

1. Several haematological and biochemical parameters were measured in the erythrocytes of the grey-headed fruit bat. 2. The level of 2,3-diphosphoglycerate was almost twice that found in human erythrocytes. Similarly pyruvate kinase activity was more than twice that of man. 3. The activities of other enzymes of the glycolytic pathway were similar to those found in man. 4. The level of reduced glutathione (GSH) and the GSH regeneration rate in the erythrocytes of the bat were comparable to those found in man.     

Enhancement of glutathione production in a coupled system of adenosine deaminase-deficient recombinant Escherichia coli and Saccharomyces cerevisiae

Adenosine triphosphate (ATP) is necessary in the enzymatic production of glutathione (GSH). Our aim was to improve GSH production by increasing the efficiency of ATP regeneration in a coupled system. Previous results suggested that low GSH production in the coupled system is due to the irreversible transformation of adenosine (Ado) to hypoxanthine (Hx) via inosine (Ino) pathway in Escherichia coli JM109 (pBV03). In this study, to block the transformation of Ado into Hx and enhance GSH production, a coupled ATP regeneration system was constructed with adenosine deaminase-deficient recombinant E. coli JW1615 (pBV03) and Saccharomyces cerevisiae WSH2. GSH production was improved (2.94-fold of the control), and ATP regeneration reaction was established in the coupled system. The results are applicable to ATP regeneration in other microbial processes.     

ATP and GSH dependence of MRP1-mediated outward translocation of phospholipid analogs in the human erythrocyte membrane

The active outward translocation of phospholipid analogues from the inner to the outer membrane leaflet of human erythrocytes by the multi-drug resistance protein MRP1 (ABCC1) depends on intracellular reduced glutathione (GSH). Entrapment of ATP and increasing amounts of GSH inside resealed ghosts prepared from erythrocytes resulted in an up to six-fold increase of the translocation rate. Entrapped oxidized glutathione (GSSG) acted inhibitory but produced stimulation after addition of the disulphide-reducing reagent dithioerythritol. Modification of GSH by esterification of the C-terminal carboxylate of Gly, removal of the N-terminal Glu or substitution of the SH group by an anionic S-dicarboxyethyl or sulphonate group abolished stimulation. The effect of S-alkylation of GSH depended on the length of the alkyl group. S-methyl GSH was somewhat more effective than GSH, but maximal stimulation was similar. S-butyl GSH acted poorly stimulatory while S-hexyl GSH was essentially ineffective. Analyses of the kinetic data of translocation revealed K(m) values for GSH and methyl-GSH of respectively 7.4 +/- 2.4 and 4.9 +/- 1.1 mmol l(-1). At high GSH levels and defined constant ATP levels using an ATP-regenerating system, the Km for ATP of the outward translocation was 0.16 +/- 0.02 mmol l(-1). In the same system lacking GSH, the Km for ATP of the inward translocation by the aminophospholipid flippase was 0.53 +/- 0.23 mmol l(-1).     

ATP and GSH dependence of MRP1-mediated outward translocation of phospholipid analogs in the human erythrocyte membrane

The active outward translocation of phospholipid analogues from the inner to the outer membrane leaflet of human erythrocytes by the multi-drug resistance protein MRP1 (ABCC1) depends on intracellular reduced glutathione (GSH). Entrapment of ATP and increasing amounts of GSH inside resealed ghosts prepared from erythrocytes resulted in an up to six-fold increase of the translocation rate. Entrapped oxidized glutathione (GSSG) acted inhibitory but produced stimulation after addition of the disulphide-reducing reagent dithioerythritol. Modification of GSH by esterification of the C-terminal carboxylate of Gly, removal of the N-terminal Glu or substitution of the SH group by an anionic S-dicarboxyethyl or sulphonate group abolished stimulation. The effect of S-alkylation of GSH depended on the length of the alkyl group. S-methyl GSH was somewhat more effective than GSH, but maximal stimulation was similar. S-butyl GSH acted poorly stimulatory while S-hexyl GSH was essentially ineffective. Analyses of the kinetic data of translocation revealed K_m values for GSH and methyl-GSH of respectively 7.4±2.4 and 4.9±1.1 mmol l^?1. At high GSH levels and defined constant ATP levels using an ATP-regenerating system, the K_m for ATP of the outward translocation was 0.16±0.02 mmol l^?1. In the same system lacking GSH, the K_m for ATP of the inward translocation by the aminophospholipid flippase was 0.53±0.23 mmol l^?1.     

生物合成谷胱甘肽种间耦合ATP再生系统的构建

利用重组大肠杆菌Ⅱ 1中的谷胱甘肽合成酶系和面包酵母WSH J7中的ATP生物合成酶系 ,构建了一个以葡萄糖为能源的种间耦合ATP再生系统。经过通透性处理的酵母细胞几乎不能消耗葡萄糖。在反应体系中添加 1mmol/LAMP和 0 0 5mmol/LNADH ,即可启动酵母的酵解途径。提高耦合系统中的葡萄糖浓度 ,可促进GSH的合成。当葡萄糖浓度为 40 0mmol/L时 ,系统内GSH浓度达到 1 0 4mmol/L(3 2 g/L)。Mg2 +缺乏时 ,耦合系统和外加ATP的非耦合系统均不能合成谷胱甘肽。耦合系统中Mg2 +与ATP形成螯合物 ,可能是导致耦合系统中GSH产量较低的原因。在耦合系统中补加Mg2 +,反应 6h时GSH浓度达到 1 4 3mmol/L(4 4g/L)。     

Enzymatic glutathione production using metabolically engineered <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> as a whole-cell biocatalyst

We developed a novel enzymatic glutathione (GSH) production system using Saccharomyces cerevisiae as a whole-cell biocatalyst, and improved its GSH productivity by metabolic engineering. We demonstrated that the metabolic engineering of GSH pathway and ATP regeneration can significantly improve GSH productivity by up to 1.7-fold higher compared with the parental strain, respectively. Furthermore, the combination of both improvements in GSH pathway and ATP regeneration is more effective (2.6-fold) than either improvement individually for GSH enzymatic production using yeast. The improved whole-cell biocatalyst indicates its great potential for applications to other kinds of ATP-dependent bioproduction.     

Comparative red blood cell metabolism in three wallaby species, Macropus eugenii, Macropus parma and Thylogale thetis (Macropodidae: Marsupialia)

Aspects of red blood cell metabolism were compared among three species of small macropodid marsupials from different habitats. Packed cell volume (PCV), erythrocyte reduced glutathione (GSH) concentration and GSH regeneration rates were similar in all three species. The Parma wallaby had very low red cell potassium levels compared to the other species studied. The Tammar wallaby had higher rates of glucose consumption and lactate production in vitro at both pH 7.4 and 8.2 than did the Parma and significantly lower adenosine triphosphate (ATP) levels than the other species. These findings are consistent with preliminary reports published previously. The differences noted cannot be directly related to differences in the habitats of the species.     

Effect of factors of favism on the protein and lipid components of rat erythrocyte membrane

Erythrocytes prepared from riboflavin- and tocopherol-deficient (RT^?) and from control rats were used to investigate the mechanism of oxidative hemolysis by the factors of favism. RT^? erythrocytes have a defense system against the oxidative stress which is blocked either where regeneration of GSH occurs or the scavenging of the radicals from the membrane is prevented. The oxidative factors used were isouramil, divicine and diamide. When RT^? erythrocytes were treated with isouramil, GSH decreased to undetectable levels and was not regenerated. Complete hemolysis occurred, but no oxidation of SH groups of membrane proteins or formation of spectrin polymers was detected. A similar effect was observed with diamide. However, SH groups of membrane proteins were completely oxidized and spectrin polymers were formed. Extensive lipid peroxidation was also detected together with a 30% fall in the arachidonic acid level. Control erythrocytes treated with either isouramil or diamide were not hemolyzed. When treated with isouramil, after a fall in the first few minutes, the GSH level was completely regenerated after 20 min. Incubation with diamide caused extensive oxidation of SH groups of membrane proteins and formation of spectrin polymers. No lipid peroxidation was detected after treatment with isouramil, but the same decrease of arachidonic acid occurred as in RT^? erythrocytes. These results support the hypothesis that oxidative hemolysis by the factors of favism is caused by uncontrolled peroxidation of membrane lipids.     

The influence of 2-chlorodeoxyadenosine (2-CdA) on the adenine energy charge and glutathione content of human erythrocytes

We have examined the effect of exposure of human erythrocytes to the new chemotherapy drug 2-chlorodeoxyadenosine (2-CdA, cladribine), focusing on the glutathione (GSH and GSSG) content and the adenine energy charge (AEC). Incubation of erythrocytes with 0.1-5 microg/ml 2-CdA induced no significant change in the reduced or total glutathione level or in the AMP and ATP concentrations. The ADP concentration increased slightly and the AEC value is in the range typical of healthy organisms. Incubation of erythrocytes with 2-CdA also caused cell shape changes, converting most of the cells to echinocytes.     

2,4,5-T and 2,4,5-TCP induce oxidative damage in human erythrocytes: the role of glutathione

The molecular basis of the toxic properties of phenoxy herbicides in humans and animals has been insufficiently studied. In this study, damage parameters [levels of reduced glutathione (GSH) and total glutathione; activity of glutathione reductase (GR); activities of catalase (CAT) and superoxide dismutase (SOD); levels of adenine nucleotides and adenine energy charge (AEC)] were measured in human erythrocytes exposed in vitro to 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and its metabolite 2,4,5-trichlorophenol (2,4,5-TCP). Both 2,4,5-T and 2,4,5-TCP decreased the level of reduced glutathione (GSH) in erythrocytes in comparison to the control, but did not significantly change the total glutathione (2GSH + GSSG). This suggests that GSH concentration decreases concomitantly with an increase in oxidized glutathione (GSSG). 2,4,5-TCP at 100 ppm significantly decreased catalase and SOD activities. 2,4,5-T and 2,4,5-TCP did not significantly change the activity of glutathione reductase. 2,4,5-TCP decreased the level of ATP and increased the content of ADP and AMP, indicating a fall in AEC. 2,4,5-T and 2,4,5-TCP significantly changed the erythrocyte morphology. All these data are evidence of oxidative stress in erythrocytes incubated with 2,4,5-T and 2,4,5-TCP; the stress appears to be more intense in the case of 2,4,5-TCP.     

Erythrocyte and plasma glutathione levels in patients with chronic renal insufficiency

Reduced glutathione (GSH) levels were investigated in the erythrocytes and plasma of nondialyzed patients with varying degrees of renal insufficiency and also of patients on regular hemodialysis treatment. GSH levels were from 19 to 70% higher in the erythrocytes of examined patients as compared to their corresponding age-matched controls. A correlation was found between the degree of renal insufficiency and the erythrocyte GSH level. No variations in plasma GSH levels which could be related to the degree of renal deterioration were observed. A routine hemodialysis did not significantly affect erythrocyte and plasma GSH levels. No significant differences in GSH levels between anemic and nonanemic uremic patients were observed.     

The influence of X-rays on human erythrocytes. Primary radicals

The effects on human erythrocytes of water-derived radicals generated by X-rays were studied under anaerobic conditions and in the presence of oxygen. Erythrocyte damage was estimated on the basis of the reduced GSH and MetHb content in the erythrocytes, the -SH group content in the membrane proteins and the amount of K(+)released from the erythrocytes. The results obtained show that the level of reduced GSH was the most sensitive indicator of erythrocyte damage by X-rays followed by the efflux of K(+). The processes of GSH oxidation took place most rapidly under air. At a dose of 100 Gy, the level of GSH fell to about 50%, whereas under argon and N(2)O to about 75% and 65%, respectively. A slight increase in the efflux of K(+)was observed in preparations irradiated under air. However, when erythrocytes were irradiated under argon and N(2)O, the loss of K(+)occurred at a dose 8-times higher. Changes in the remaining parameters occurred at considerably higher doses. On the basis of the results obtained one can say that oxygen is a factor increasing the toxicity of(.)OH radicals towards erythrocytes; however, e(-)(aq)present in the system can cause a decrease in damage to certain cellular components.     

Vitamin C and E combination modulates oxidative stress induced by X‐ray in blood of smoker and nonsmoker radiology technicians

X‐ray radiation is detrimental to human cells and may lead to development of life‐threatening diseases. Cigarette smoke contains about 500 chemicals that include organic and oxidant compounds whereas vitamin C and E (VCE) have scavenger effects on the compounds. We investigated effects of VCE administration on X‐ray‐induced oxidative toxicity in blood of smoker and nonsmoker X‐ray technicians. Twenty technicians and 30 healthy age‐matched subjects control were used in the study. Ten of the X‐ray technicians and 15 of the control were smokers. Blood samples were taken from the control. Oral vitamin C (500 mg) and vitamin E (150 mg) were daily supplemented to the smoker and nonsmoker X‐ray technicians for 5 weeks. Blood samples were taken from the X‐ray technicians after and before 5 weeks. Plasma and erythrocytes lipid peroxidation (LP), reduced glutathione (GSH) levels, erythrocytes glutathione peroxidase (GSH‐Px), and plasma antioxidant vitamin concentrations were investigated in control and X‐ray technicians with smoker and nonsmoker. Plasma and erythrocytes LP levels were higher in the total X‐ray group and smoker X‐ray group than in control and nonsmoker X‐ray group, respectively although the LP level was decreased by the VCE treatment. The plasma vitamin C, vitamin A, vitamin E, and β‐carotene concentrations were lower in the X‐ray group than in control although their concentrations were increased by the treatment. The erythrocytes GSH level and GSH‐Px activity were found to be higher in the treatment group than in the X‐ray group. Plasma GSH level was not found to be different in all group. Reactive oxygen species may play role in the mechanism that has been proposed to explain the biological side effect of X‐ray radiation and smoke. VCE prevents the smoke and X‐ray‐induced oxidative stress to strengthen antioxidant vitamin concentrations in the blood of the technicians. Copyright © 2009 John Wiley & Sons, Ltd.     

Evidence for a role of taurine in the in vitro oxidative toxicity of neutrophils toward erythrocytes

Production of hydrogen peroxide and secretion of myeloperoxidase by stimulated neutrophils resulted in myeloperoxidase-catalyzed oxidation of chloride to hypochlorous acid (HOCl), the reaction of HOCl with taurine to yield taurine monochloramine (TauNHCl), and accumulation of TauNHCl in the extracellular medium. When erythrocytes were present, the yield of TauNHCl was lower as the result of uptake of TauNHCl into erythrocytes. The zwitterion taurine was not taken up, but the anion TauNHCl and other anionic oxidants including taurine dichloramine (TauNCl2) and L-alanine chloramines were transported into erythrocytes by the anion-transport system. Oxidation of intracellular components such as glutathione (GSH) by taurine chloramines resulted in reduction of the chloramines and trapping of taurine within erythrocytes. At high oxidant:erythrocyte ratios, TauNHCl also oxidized hemoglobin (Hb) and depleted ATP, but caused little lysis. TauNCl2 was much more effective as a lytic agent. At low oxidant:erythrocyte ratios, the chloramines caused net loss of GSH when no glucose was provided, but Hb was not oxidized and GSH content returned to normal when glucose was added. Therefore, anionic chloramines may mediate oxidative toxicity when the neutrophil:erythrocyte ratio is high. Under more physiologic conditions, chlorination of taurine by neutrophils and the uptake and reduction of TauNHCl by erythrocytes prevents accumulation of oxidants and may protect blood cells, plasma components, and tissues against oxidative toxicity.     

Dinitrophenyl S-glutathione ATPase purified from human muscle catalyzes ATP hydrolysis in the presence of leukotrienes.

Dinitrophenyl S-glutathione (Dnp-SG) ATPase has been purified from human muscle to apparent homogeneity using Dnp-SG affinity chromatography and immunoaffinity chromatography using antibodies raised against human erythrocyte Dnp-SG ATPase. The enzyme purified from human muscle showed a subunit M(r) value of about 38 kDa in denaturing gels. The M(r) value of the native enzyme as determined by Sephadex G-200 gel filtration was found to be about 80 kDa, which indicates that it is a dimer. The N-terminus of the enzyme was blocked. Its immunological and kinetic properties were similar to Dnp-SG ATPase of human erythrocytes. Besides catalyzing the ATP hydrolysis in the presence of Dnp-SG, the muscle enzyme also catalyzed ATP hydrolysis in the presence of various leukotrienes, namely LTC4.LTD4, LTE4, and N-acetyl LTE4. The specific activity of the enzyme toward LTC4 was relatively higher than other GSH-xenobiotic conjugates. The muscle enzyme exhibits a low Km value for all leukotrienes as compared to Dnp-SG, indicating high affinity of the enzyme for leukotrienes as activators. The enzyme also catalyzed ATP hydrolysis in the presence of GSH conjugates of endogenously generated fatty acid epoxides. Our results might suggest that Dnp-SG ATPase is involved in the transport of GSH conjugates, leukotrienes, and other organic anions in muscle, erythrocytes, liver, and probably other tissues.     

The transport of oxidized glutathione from the erythrocytes of various species in the prescence of chromate

1. Erythrocytes from normal and glucose 6-phosphate dehydrogenase-deficient humans were subjected to hydrogen peroxide diffusion to oxidize the GSH. Studies were carried out in the presence and absence of chromate to inhibit glutathione reductase and with or without the addition of glucose. 2. The GSH content of erythrocytes from other species was oxidized by subjecting them to hydrogen peroxide diffusion in the presence of chromate and glucose. 3. Chromate (1.3mm) inhibited glutathione reductase by about 80%, whereas glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphofructokinase and pyruvate kinase were not inhibited. 4. The GSSG formed was transported from the erythrocytes to the medium. 5. The transport rate of GSSG from glucose 6-phosphate dehydrogenase-deficient erythrocytes subjected to hydrogen peroxide diffusion in the presence of chromate was comparable with that from normal and glucose 6-phosphate dehydrogenase-deficient erythrocytes. 6. The rate of transport of GSSG from erythrocytes of various species studied could be ranked: pigeon>rabbit>rat>donkey>man>dog>horse>sheep>chicken>fish.     

Studies in the enzymology of glutathione metabolism in human erythrocytes

Spectrophotometric assay methods are described for glutathione synthetase, gamma-glutamylcysteine synthetase and gamma-glutamyl transpeptidase of erythrocytes. The contents of these enzymes in normal human erythrocytes are reported. Erythrocyte glutathione synthetase is inhibited by ADP; this inhibition is competitive with respect to ATP. gamma-Glutamylcysteine synthetase is subject to feedback inhibition by GSH, and is also inhibited by NADH, and to a lesser extent by NAD(+) and NADPH. This enzyme is irreversibly inactivated by cysteamine.     

Increased efflux of oxidized glutathione (GSSG) causes glutathione depletion and potentially diminishes antioxidant defense in sickle erythrocytes

Erythrocytes are both an important source and target of reactive oxygen species in sickle cell disease. Levels of glutathione, a major antioxidant, have been shown to be decreased in sickle erythrocytes and the mechanism leading to this deficiency is not known yet. Detoxification of reactive oxygen species involves the oxidation of reduced glutathione (GSH) into glutathione-disulfide (GSSG) which is actively transported out of erythrocyte. We questioned whether under oxidative conditions, GSSG efflux is increased in sickle erythrocytes. Erythrocytes of 18 homozygous sickle cell patients and 9 race-matched healthy controls were treated with 2,3-dimethoxy-l,4-naphthoquinone, which induces intracellular reactive oxygen species generation, to stimulate GSSG production. Intra- and extracellular concentrations of GSH and GSSG were measured at baseline and during 210-minute 2,3-dimethoxy-l,4-naphthoquinone stimulation. While comparable at baseline, intracellular and extracellular GSSG concentrations were significantly higher in sickle erythrocytes than in healthy erythrocyte after 210-minute 2,3-dimethoxy-l,4-naphthoquinone stimulation (69.9 ± 3.7 μmol/l vs. 40.6 ± 6.9 μmol/l and 25.8 ± 2.7 μmol/l vs. 13.6 ± 1.7 μmol/l respectively, P<0.002). In contrast to control erythrocytes, where GSH concentrations remained unchanged (176 ± 8.4 μmol/l vs. 163 ± 13.6 μmol/l, NS), GSH in sickle erythrocytes decreased significantly (from 167 ± 8.8 μmol/l to 111 ± 11.8 μmol/l, P<0.01) after 210-minute 2,3-dimethoxy-l,4-naphthoquinone stimulation. Adding multidrug resistance-associated protein-1 inhibitor (MK571) to erythrocytes blocked GSSG efflux in both sickle and normal erythrocytes. GSSG efflux, mediated by multidrug resistance-associated protein-1, is increased in sickle erythrocytes, resulting in net loss of intracellular glutathione and possibly higher susceptibility to oxidative stress.