Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A highly purified plasma membrane fraction isolated from rat hepatocytes was found to catalyze the hydrolysis of ATP in response to micromolar concentrations of glutathione disulfide (GSSG). This process exhibited distinct kinetic parameters suggesting the existence of both a high and low affinity component. The apparent Km values (GSSG) for ATP hydrolysis were 140 microM and 1 mM for the high affinity and low affinity components, respectively. Disulfides other than GSSG were also found to stimulate ATP hydrolysis. The similarity between the kinetic properties of the GSSG-stimulated ATPase and those reported for GSSG transport in erythrocytes (Kondo, T., Dale, G. L., and Beutler, E. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 6359-6362) suggests that the ATPase may function in the active extrusion of intracellular GSSG.
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PMID:Demonstration and partial characterization of glutathione disulfide-stimulated ATPase activity in the plasma membrane fraction from rat hepatocytes. 315 27

The protective effect of geraniin (tannin from Geranium thunbergii) against oxidative damage was examined in the mouse ocular lens. Oxidative damage in the lens was induced by diamide, diazene dicarboxylic acid bis (N,N-dimethylamide); diamide oxidized the sulfhydryl groups in both the membrane and cytoplasm but did not increase lipid peroxide. Geraniin showed protective effects on the changes in the Na+/K+ ratio, GSH level, Na,K-ATPase activity, GSH reductase activity and the sulfhydryl level of the membranous protein in the diamide-treated lens, but such protective effects of geraniin were not observed in the cell-free system of the lens. In addition, geraniin itself was unable to reduce GSSG to GSH and also unable to inhibit the oxidative reaction of the sulfhydryl group to diamide. These results suggest that in the intact lens geraniin would act primarily on the lens cell membrane surface to inhibit an influx of diamide into the inner part of the plasma membrane and the cytoplasm, and consequently that geraniin may protect sulfhydryl groups in the cell membrane and cytoplasm from their oxidation by diamide and keep the redox system of the lens in a normal state.
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PMID:Effect of tannin on oxidative damage of ocular lens. 318 50

This paper reports inhibition of Na(+) + K(+)-stimulated, ouabain-inhibited adenosine triphosphatase (S-ATPase) in sheep red cell membranes by oxidized glutathione (GSSG). The results are consistent with the hypothesis that this inhibition depends upon the formation of a mixed disulfide between glutathione and -SH group(s) in the enzyme protein. Thus, inhibition of S-ATPase by GSSG proceeds more rapidly at alkaline than at neutral pH and is reversed by the addition of an excess of a compound containing reduced -SH groups (e.g. dithiothreitol). ATP protects S-ATPase against inhibition by GSSG and this protection depends on both the monovalent and divalent cation composition of the medium. Protection by ATP is more complete in the presence of K(+) than in the presence of Na(+).
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PMID:Inhibition of adenosine triphosphatase in sheep red cell membranes by oxidized glutathione. 424 9

Reduced glutathione (0.3 mM) stimulates the activity of sodium-potassium activated ATPase (Na+K+ATPase) by 54% in plasma membranes prepared from bovine corneal endothelial cells. Oxidized glutathione, however, has no effect on Na+K+ATPase activity in the same tissue, although it does inhibit magnesium activated ATPase (Mg++ATPase) by approximately 30%. Adenosine neither stimulates nor inhibits either Na+K+ATPase or Mg++ATPase in these plasma membranes. It is postulated that the stimulatory effect of glutathione on deturgescence stems from the direct reaction of the reduced form of the tripeptide on sulfhydryl groups located on plasma membranes of corneal endothelial cells. It is highly probable that these sulfhydryl groups are part of the Na+k+ATPase complex itself.
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PMID:The effects of glutathione and adenosine on plasma membrane ATPases of the corneal endothelium. An hypothesis on the stimulatory mechanism of perfused glutathione upon deturgescence. 627 70

The mammalian lens contains an unusually high concentration of glutathione (GSH), the highest level being in the epithelium. GSH is present largely in the reduced state. The high concentration of GSH in a normal lens and the decreased concentration in most types of cataracts have led to many hypotheses on its role in cataract formation. These hypotheses are considered in the light of current evidence. GSH is synthesized and degraded in the lens. Both processes require ATP, derived largely from glycolysis. Carbohydrate metabolism is also involved in the maintenance of GSH in the reduced state. There is a direct link between the rate of formation of oxidized glutathione (GSSG) and the stimulation of the hexose monophosphate shunt through the generation of NADPH. One possible function of GSH in the lens is to maintain the thiol (SH) groups of proteins in the reduced state, thus preventing formation of high molecular weight (HMW) protein aggregates. The formation of HMW proteins in X-ray-induced cataracts through disulphide bond formation and the involvement of SH oxidation in HMW proteins isolated from human cataractous lenses suggest a role for GSH in protecting protein SH groups. GSH in the lens may also protect critical SH groups involved in regulating cation transport and permeability. Studies with mammalian lenses indicate that lowering the lens GSH concentration leads to increased permeability to cations and inactivation of Na+,K+-ATPase. A consequence of the changes in ion distribution is the inhibition of protein synthesis, which may explain the cessation of growth in cataractous lenses. GSH may also protect against oxidative damage to the lens. GSH metabolism is intimately involved in detoxification of H2O2, normally present in the aqueous humour. Lenses with impaired shunt activity or inhibited glutathione reductase are more susceptible to oxidative damage by peroxide. This may contribute to the formation of cataract.
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PMID:Metabolism and function of glutathione in the lens. 656 81

Cadmium chloride (CdCl2)-induced biochemical changes were characterized in male, CD-1 mouse testes. CdCl2 inhibited the testes microsomal Na+,K(+)-ATPase activity in vitro and in vivo. The inhibitory range was 30-50 microns and the concentration for half maximal inhibition (IC50 value) was 90 microns over 5 min preincubation. CdCl2 (2mg/kg/day, s.c.) for 2 days significantly inhibited testes Na+,K(+)-ATPase (near 90% inhibition). The content of testicular GSH and the ratio of reduced glutathione (GSH)/GSSG (oxidized glutathione) decreased in CdCl2-treated groups. Using salicylate as a trapping agent and high pressure liquid chromatography with electrochemical detection (LCED), we measured the OH production in vivo. 2,5-dihydroxybenzoic acid (2,5-DHBA) and 2,3-dihydroxybenzoic acid (2,3-DHBA) as indices of hydroxyl free radical formation significantly increased after 5 days CdCl2 exposure. Pretreatment with vitamin E (20 mg/kg, s.i.d., i.m., 7d) protected CdCl2-induced increase in OH. generation in testes. From this study, it was demonstrated that CdCl2 induced testicular toxicity could possibly be mediated by a significant increase in hydroxyl free radical formation and a reduction in GSH content and Na+,K(+)-ATPase activity. Vitamin E seems to prevent the CdCl2 induced increase in hydroxyl free radical generation.
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PMID:Na+, K(+)-ATPase, glutathione, and hydroxyl free radicals in cadmium chloride-induced testicular toxicity in mice. 766 26

Oxidative stress is associated with the formation of oxidized glutathione (GSSG) in the cells, which can form mixed disulfide with proteins leading to alteration of their function. The present study looks at the effect of in vitro exposure of GSSG on intestinal mitochondria and brush border membrane (BBM). Incubation with 1 mM GSSG increased the protein bound GSH in mitochondria by 15-fold. This was associated with loss of activity of certain mitochondrial enzymes such as succinic dehydrogenase, isocitrate dehydrogenase, total ATPase and NADH dehydrogenase whereas NADH oxidase was not affected. A similar treatment of BBMV with GSSG increased the protein bound GSH by 4.7-fold without altering its enzyme activity. Exposure to GSSG had no effect on the Na(+)-dependent glucose transport by BBMV. These studies suggest that GSSG formed during oxidative stress may modify thiol groups in proteins by forming mixed disulfides leading to functional alteration of certain cellular proteins.
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PMID:Effect of oxidized glutathione on intestinal mitochondria and brush border membrane. 767 Nov 37

It was reported previously that dietary ascorbate (ASC) delays the development of galactose-induced cataract in guinea pigs compared to the rate which is observed in ASC-deficient animals. Experiments were conducted to explore the possible mechanism of this phenomenon. Guinea pigs were fed for a period of up to 4 weeks either a normal diet (1 g ASC/kg diet) or a scorbutic diet (< 0.04 g ASC/kg diet) combined with 10% galactose in the drinking water. After 2 weeks, levels of ASC in animals on the scorbutic diet decreased by 95% in the aqueous humor and by 78% in the lens. Slit lamp examination showed that galactose-induced vacuoles in the lens equator formed at a significantly faster rate in the scorbutic animals. However, examination of biochemical parameters in whole lenses of the two groups of animals after 2 weeks showed no significant differences with regard to accumulation of galactose and galactitol, decreases in the levels of myoinositol, taurine and GSH or changes in cation concentrations. In order to examine possible regional changes in the lenses, various parameters were studied in the lens capsule-epithelium. On day 4, the capsule epithelia of scorbutic animals on a galactose diet had a content of galactitol two-and-a-half times higher than that of normal galactose-fed animals. Scorbutic conditions also intensified the loss of Na(+)-K+ ATPase activity in the lens capsule-epithelium caused by galactose feeding. Oxidized glutathione was not detectable in the lens capsule epithelia of any of the animals studied. Hexose monophosphate shunt activity was elevated in lenses of normal galactose-fed animals during the first hour of culture after death whereas lenses of scorbutic galactose-fed animals were not. Consistent with the in vivo findings, galactitol accumulation in dog lens epithelial cells exposed to 30 mM galactose was significantly inhibited by the presence of either ASC or dehydroascorbate (DHA) in the medium. Hexose monophosphate shunt activity in the cells was stimulated to two-and-a-half times its initial level by either 1 mM DHA or 30 mM galactose and slightly more than three-fold by a combination of the two challenges. The results suggest that decreased polyol accumulation in the lens epithelium of the normal galactose-fed guinea pig, which has a high level of ASC in the aqueous humor, accounts for the delay in onset of cataract compared to that for the ASC-deficient animal.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:A physiological level of ascorbate inhibits galactose cataract in guinea pigs by decreasing polyol accumulation in the lens epithelium: a dehydroascorbate-linked mechanism. 815 13

Extracorporeal dialysis in uremic subjects produces erythrocyte alterations on energetic and redox metabolism. On this basis, we have tried to verify a fundamental parameter for the integrity of the red blood cell namely the glutathione content both in the oxidized and reduced form. Comparisons were made between two groups of subjects (similar in age, sex and number). One group consisted of uremic subjects undergoing dialysis and the other in healthy controls. As well as a slight increase in reduced glutathione (GSH), an accumulation of oxidized glutathione (GSSG) was found which, in postdialysis patients, reached values up to 3 times higher than in controls. This means a lowering in the ratio GSH/GSSG. There was also a decrease in total Mg(++)-ATPase activity, significantly found in erythrocyte ghosts of postdialysis patients. The hypothesis of a reduced efflux of GSSG as well as an increase in its formation speed (activation of glutathione peroxidase) is taken into consideration.
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PMID:[Extracorporeal hemodialysis: various++ metabolic and erythrocyte-membrane features of uremic subjects]. 832 84

We evaluated the specific effects of acrolein on sulfhydryl status and plasma membrane-dependent functions of cultured pulmonary artery endothelial cells. Acrolein exposure caused a dose-dependent increase in lactate dehydrogenase (LDH) release and decreases in reduced glutathione (GSH) and protein sulfhydryl (P-SH) content, whereas oxidized glutathione (GSSG) content was not altered. Exposure to 4.5 microM, but not 1.5 or 3.0 microM, of acrolein caused significant (p < 0.05) LDH release. With increasing concentrations (25 microM) of acrolein, LDH release was increased to 66% (p < 0.001). Acrolein (3.0-25 microM) resulted in 36 to 100% reductions in GSH content, whereas reductions in P-SH content at these concentrations of acrolein ranged from 11 to 37%. Uptake of amino acids (cystine, glycine, and glutamic acid) and incorporation of valine into the protein fraction were significantly reduced in a dose-dependent fashion in acrolein (1.5-4.5 microM)-exposed cells. Reductions in cystine, glycine, and glutamic acid uptakes were maximal in cells exposed to 3 and 4.5 microM acrolein (p < 0.001). Similarly, maximum reductions (p < 0.001) in both uptake and incorporation of valine into the protein fraction were observed at 3.0 and 4.5 microM acrolein. Acrolein (1.5 microM) also resulted in significant loss of plasma membrane-specific Na+/K(+)-ATPase as well as plasma membrane P-SH content (p < 0.05 for both). When cells were treated with ouabain, reductions in amino acid uptake were observed, and this appeared to mimic the effect of acrolein exposure. When isolated plasma membranes were exposed to a known SH-alkylating agent, N-ethylmaleimide, losses of Na+/K(+)-ATPase and P-SH content were observed and were similar to the effects following exposure to acrolein. These results demonstrate that acrolein exposure results in alterations of plasma membrane-dependent transport in pulmonary artery endothelial cells, leading to reduced availability of precursor amino acids used in GSH and protein synthesis. This plasma membrane injury is accompanied by reductions in the GSH and P-SH contents of these cells. Loss of the plasma membrane P-SH appears to be associated with specific inactivation of Na+/K(+)-ATPase.
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PMID:Acrolein-induced injury to cultured pulmonary artery endothelial cells. 839 54


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