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)

Methylxanthines (MX) inhibit cell division in sea urchin and clam eggs. This inhibitory effect is not mediated via cAMP. MX also inhibit respiration in marine eggs, at concentrations which inhibit cleavage. Studies showed that no changes occurred in ATP and ADP levels in the presence of inhibitory concentrations of MX, indicating an extra-mitochondrial site of action for the drug. Subsequent studies revealed decreased levels of NADP+ and NADPH, when eggs were incubated with inhibitory concentrations of MX, but no change in levels of NAD+ and NADH. MX did not affect the pentose phosphate shunt pathway and did not have any effect on the enzyme NAD+ -kinase. Further studies showed a marked inhibitory effect on the glutathione reductase activity of MX-treated eggs. Reduced glutathione (GSH) could reverse the cleavage inhibitory effect of MX. Moreover, diamide, a thiol-oxidizing agent specific for GSH in living cells, caused inhibition of cell division in sea urchin eggs. Diamide added to eggs containing mitotic apparatus (MA) could prevent cleavage by causing a dissolution of the formed MA. Both MX and diamide inhibit a Ca2+-activated ATPase in whole eggs. The enzyme can be reactivated by sulfhydryl reducing agents added in the assay mixture. In addition, diamide causes an inhibition of microtubule polymerization, reversible with dithioerythritol. All experimental evidence so far suggests that inhibition of mitosis in sea urchin eggs by MX is mediated by perturbations of the in vivo thiol-disulfide status of target systems, with a primary effect on glutathione levels.
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PMID:Effects of caffeine and other methylxanthines on the development and metabolism of sea urchin eggs. Involvement of NADP and glutathione. 1 15

In the presence of glucose (2 mg/ml), leucine (10 mM) noticeably increased islets' NADPH contents as well as the NADPH:NADP ratio; the changes occurred as soon as 1 min after its addition. NADH concentrations were also increased by leucine. The NADPH:NADP ratio as well as insulin release stimulated by glucose plus leucine were markedly decreased by methylene blue. The thiol oxidants diamide and tert-butyl hydroperoxide also inhibited insulin secretion in response to glucose plus leucine. Employing the perfused pancreas technique, the insulin-releasing action of p-chloromercuribenzoate was further enhanced by leucine. The combined effects were inhibited by tert-butyl hydroperoxide, however. Our data suggest that the insulin-releasing action of leucine depends on the islets' NADPH and reduced glutathione (GSH); in addition, leucine may contribute to insulin secretion by increasing the islet NADPH:NADP ratio and the NADH:NAD ratio. From the data, we assume that the observed increase of NADPH may lead via GSH to an increase in the number of such thiol groups in the beta-cell membrane, which are believed to be related to stimulation of insulin release and, thus, to increase the sensitivity of the beta-cell to stimulation by glucose and/or leucine.
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PMID:Effect of leucine on the pyridine nucleotide contents of islets and on the insulin released--interactions in vitro with methylene blue, thiol oxidants, and p-chloromercuribenzoate. 3 18

Glutathione reductase from the liver of DBA/2J mice was purified to homogeneity by means of ammonium sulfate fractionation and two subsequent affinity chromatography steps using 8-(6-aminohexyl)-amino-2'-phospho-adenosine diphosphoribose and N6-(6-aminohexyl)-adenosine 2',5'-biphosphate-Sephadex columns. A facile procedure for the synthesis of 8-(6-aminohexyl)-amino-2'-phospho-adenosine diphosphoribose is also presented. The purified enzyme exhibits a specific activity of 158 U/mg and an A280/A460 of 6.8. It was shown to be a dimer of Mr 105000 with a Stokes radius of 4.18 nm and an isoelectric point of 6.46. Amino acid composition revealed some similarity between the mouse and the human enzyme. Antibodies against mouse glutathione reductase were raised in rabbits and exhibited high specificity. The catalytic properties of mouse liver glutathione reductase have been studied under a variety of experimental conditions. As with the same enzyme from other sources, the kinetic data are consistent with a 'branched' mechanism. The enzyme was stabilized against thermal inactivation at 80 degrees C by GSSG and less markedly by NADP+ and GSH, but not by NADPH or FAD. Incubation of mouse glutathione reductase in the presence of NADPH or NADH, but not NADP+ or NAD+, produced an almost complete inactivation. The inactivation by NADPH was time, pH and concentration dependent. Oxidized glutathione protected the enzyme against inactivation, which could also be reversed by GSSG or other electron acceptors. The enzyme remained in the inactive state even after eliminating the excess NADPH. The inactive enzyme showed the same molecular weight as the active glutathione reductase. The spectral properties of the inactive enzyme have also been studied. It is proposed that auto-inactivation of glutathione reductase by NADPH and the protection as well as reactivation by GSSG play in vivo an important regulatory role.
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PMID:Mouse-liver glutathione reductase. Purification, kinetics, and regulation. 3 57

A simple and rapid colorimetric method for the assay of erythrocyte and plasma glutathione reductase (GR) activity is described. The method is based on the colorimetric measurement of reduced glutathione (GSH) (1) produced when the enzyme is incubated with oxidised glutathione (GSSG) in the presence of either reduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate (NADPH). Results of investigations on the effects of substrate and coenzyme concentrations, pH, EDTA, sodium/potassium chloride, and time, on enzyme activity are presented. Erythrocyte and plasma NADH-GR and NADPH-GR activities in 100 healthy blood donors, and 85 cord blood samples and plasma NADH-GR and NADPH-GR levels in patients with various disease conditions are given.
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PMID:A new colorimetric method for the determination of NADH/NADPH dependent glutathione reductase in erythrocytes and in plasma. 23 82

The influence of sodium nitroprusside (SNP) on mitochondrial respiration was examined in rat liver mitochondria. The addition of SNP 1 mmol litre-1 during state 3 respiration inhibited the oxygen uptake by 63.4%. A mixture of SNP 1 mmol litre-1 and glutathione (GSH) 1 mmol litre-1 inhibited the oxygen uptake more markedly (by 75.9%). The cyanide concentrations were 0.01 mmol litre-1 with SNP alone and 0.15 mmol litre-1 with the mixture of SNP and GSH. Cyanide production from SNP in the presence of various reducing agents was studied in potassium phosphate 0.1 mol litre-1 buffer solution (pH 7.4) incubated at 37 degrees C. Cyanide was liberated markedly from SNP in the presence of GSH or ascorbate. Less cyanide was produced in the presence of NADH or NADPH. The rate of production of cyanide was dependent entirely upon the concentration of each reducing agent added. No cyanide was liberated when sodium dithionite or the oxidized forms of GSH, NAD or NADP were used. It was concluded that SNP is degradated to cyanide by a hydrogen donor and that the cyanide liberated in this manner inhibits the cytochrome oxidase activity of mitochondria in vivo.
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PMID:Inhibition of mitochondrial respiration by sodium nitroprusside and the mechanism of cyanide liberation. 58

Both di- and triglycerides were synthesized when microsomes isolated from mammary glands of lactating mice were incubated with dihydroxyacetone phosphate (DHAP), 1(-14)C)palmitate, ATP, CoASH, GSH, KF, MgC12, and NADPH. When NADH replaced NADPH, glyceride synthesis was very low. In the absence of either NADPH or NADH, DHAP was acylated to palmityl-DHAP. Since microsomes do not have glycerol 3-phosphate NAD:oxidoreductase activity , we inferred that glycerol 3-phosphate (GP) is not an intermediate in triglyceride biosynthesis from DHAP. This reductase, present in the cytosol, was active only with NADH. With the same concentration of either GP or DHAP, microsomes yielded essentially similar amounts of di- and triglycerides. Mitochondria, while capable of synthesizing palmityl-DHAP, did not produce di- and triglycerides.
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PMID:Triglyceride synthesis from dihydroxyacetone phosphate and palmitate by microsomes from mammary glands of lactating mice. 62 19

Liver microsomal enzyme activities and glutathione (GSH) contents of fasted male rats pretreated with phenobarbital (PBT) or vehicle controls were measured during and after exposure to trichloroethylene (TRI) (1% x 2 hr). TRI caused morphologic liver injury only in the pbt animals. Cytochrome P-450 and b5 contents were diminished by the end of the first hr of TRI exposure and NADH-cytochrome c reduction increased three-fold by eight hr in the PBT animals. The only change in vehicle animals exposed to TRI was a decrease in NADPH-cytochrome c reductase activity by eight hr. Hepatic GSH contents of vehicle animals, constant during TRI exposure, rose with time. In contrast, in PBT animals, hepatic GSH contents decreased during TRI exposure and then rebounded. Decreases in GSH were most profound in the microsomal fraction. When fed animals with approximately two-fold higher hepatic GSH levels than fasted animals were exposed to TRI, they had shorter anesthesia recovery times and less liver injury, although excreting similar or slightly more trichlorinated metabolite into their urine in 24 hr than their fasted counterparts. We suggest that the hepatoxic effects of trichloroethylene are caused by inadequate detoxification of its reactive intermediates.
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PMID:Trichloroethylene-induced deactivation of cytochrome P-450 and loss of liver glutathione in vivo. 84 Nov 73

Ascorbic acid and dehydroascorbic acid penetrate the human erythrocyte membrane. In vitro methemoglobin is reduced nonenzymatically by both substances in concentrations of 10(-2) M to 10(-3) M. Dehydroascorbic acid is reduced nonenzymatically to ascorbic acid by GSH, even with low GSH-content of erythrocytes. Under physiological conditions ascorbic acid induced methemoglobin reduction is far less important than reduction by the NADH dependent methemoglobin reductase system. In methemoglobinemic conditions caused by toxic effects or by congenital methemoglobin reductase deficiency treatment with ascorbic acid is possible. However, critically increased methemoglobin content of the blood higher than 30% makes therapy with methylene blue necessary.
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PMID:[On the mechanism of ascorbic acid induced methemoglobin reduction of human erythrocytes (author's transl)]. 92 9

Some properties of [4-vinyl] chlorophyllide a reductase are described. This enzyme converts divinyl chlorophyllide a to monovinyl chlorophyllide a. The latter is the immediate precursor of monovinyl chlorophyll a, the main chlorophyll in green plants. [4-Vinyl] chlorophyllide a reductase plays an important role in daylight during the conversion of divinyl protochlorophyllide a to monovinyl chlorophyll a. [4-Vinyl] chlorophyllide a reductase was detected in isolated plastid membranes. Its activity is strictly dependent on the availability of NADPH. Other reductants such as NADH and GSH were ineffective. The enzyme appears to be specific for divinyl chlorophyllide a, and it does not reduce divinyl protochlorophyllide a to monovinyl protochlorophyllide a. The conversion of divinyl protochlorophyllide a to monovinyl protochlorophyllide a has been demonstrated in barley and cucumber etiochloroplasts and appears to be catalyzed by a [4-vinyl] protochlorophyllide a reductase [Tripathy, B.C., & Rebeiz, C.A. (1988) Plant Physiol. 87, 89-94]. On the basis of reductant requirements and substrate specificity, it is possible that two different 4-vinyl reductases may be involved in the reduction of divinyl protochlorophyllide a and divinyl chlorophyllide a to their respective 4-ethyl analogues.
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PMID:Chloroplast biogenesis: [4-vinyl] chlorophyllide a reductase is a divinyl chlorophyllide a-specific, NADPH-dependent enzyme. 139 Jun 30

Lactate dehydrogenase is known to act as a dismutase converting glyoxylate to oxalate and glycolate. LDH (sources: human erythrocytes, human plasma; rabbit muscle; rat liver) activity was assayed at 340 nm using glyoxylate (5.0 mmol/l) and NADH. The LDH activity (approx. % of control) in all the cases decreased respectively in the presence of 5.0 and 10.0 mmol/l of cysteine (45 and 20), cysteamine (45 and 20), and GSH (55 and 30). This decrease in LDH activity resulted in decreased oxalate production from glyoxylate (0.5 mmol/l). A 50% inhibition in oxalate production was observed in presence of 0.3 mmol/l cysteine, 0.35 mmol/l cysteamine, and 2.0 mmol/l GSH. The results suggest that the net LDH activity towards oxalate production may be regulated by the free SH-groups in the cell. This possibility needs evaluation as a tool to lower endogenous oxalate production and the associated risk of stone formation.
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PMID:Oxalate production from glyoxylate by lactate dehydrogenase in vitro: inhibition by reduced glutathione, cysteine, cysteamine. 141 80


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