Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chromogen ABTS is the di-ammonium salt of 2,2'-azino-di[3-ethyl-benzthiazolin-sulfonic acid (6)] routinely used in the "glucose-oxidase assay" with the peroxidase (GOD-Perid method, Boehringer). 1. The specific property of ABTS to give a stable radical cation by oxidation with hydrogen peroxide in the presence of peroxidase was used to design a kinetic method, for enzyme-activity determinations. 2. The assay is suitable for the specific oxido-reductase using oxygen as acceptor, known also as "aerobic transhydrogenases" which are H2O2 formers (EC 1.-.3.-). 3. L-Amino acid: oxygen oxidoreductase (deaminating) (EC 1.4.3.2), was used throughout, being a representative model for such determinations.
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PMID:[A kinetic method for the determination of the activity of "aerobic transhydrogenases" (author's transl)]. 24 20

This paper reports a study of changes in red blood cell enzymes and some serum parameters during and after treatment of protein-calorie malnutrition. The red cell GSH levels were low during the crisis, together with the levels of GSSG:NADPH reductase, GSH:H2O2 peroxidase, aspartate aminotransferase and alanine aminotransferase. After treatment the levels of all these enzymes increased significantly to normal values. Of the serum parameters investigated, significant reduction in the activity of the enzymes cholinesterase, catecholamine oxidase, total proteins, albumin, urea and electrolytes were obvious, and returned to normal values after treatment. Ceruloplasmin activity remained low even after three weeks' treatment and could not be related to copper levels. The results are discussed in relation to anemia and liver damage that may accompany the syndrome.
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PMID:Protein-calorie malnutrition: a study of red blood cell and serum enzymes during and after crisis. 82 Apr 94

The report by Schacter et al. (J Biol Chem 247: 3601, 1972) that an antibody to NADPH-cytochrome c oxidoreductase inhibited NADPH-cytochrome c reductase and heme oxygenase activities in rat and pig liver and spleen microsomes demonstrated the role of this flavoprotein in microsomal heme oxygenation. Recent studies from other laboratories (Yoshida et al., J Biochem 75, 1187: 1974 and Bissell et al., Fed Proc 33: 1246, 1974) have strongly suggested that cytochrome P-450 is not involved in heme oxygenation. The availability of a homogeneous preparation of NADPH-cytochrome c reductase prompted us to test heme oxygenase activity in a system devoid of hemoprotein contamination. NADPH-cytochrome c reductase catalyzed biliverdin formation at a rate of 8.26 +/- 0.5 SEM nmole min-1mg-1 in the absence of biliverdin reductase. The rate of bilirubin formation in the presence of biliverdin reductase was less than 10% of the rate of biliverdin formation, suggesting that mixture of biliverdin isomers may be produced. Biliverdin production was potently (70--80%) inhibited by catalase, but was unaffected by superoxide dismutase. Epinephrine also inhibited heme oxygenation, presumably by utilizing O2. required for the formation of H2O2 by the reductase. By extrapolation, the NADPH oxidase activity due to NADPH-cytochrome c reductase can account for heme degradation occurring in microsomes. However, the specificity of ring scission at the IXalpha position must be due to another microsomal protein, perhaps the heme oxygenase of Yoshida et al., and not cytochrome P-450.
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PMID:The catalysis of heme degradation by purified NADPH-cytochrome C reductase in the absence of other microsomal proteins. 82 31

A 37-yr-old woman with nontoxic goiter is presented. The thyroid 131I uptake at 3 and 24 hr were, respectively, 77.1% and 81.4% dose. Thiocyanate discharged 65.5% of the accumulated 131I in 30 min. In vitro organification of iodine in the thyroid homogenate from the patient was impaired and it was restored to normal by the addition of H2O2, glucose, and glucose oxidase system, FAD, or reduced cytochrome b5. Riboflavin, FMN, oxidized cytochrome b5, oxidized or reduced cytochrome c, NAD(H), and NADP(H) were ineffective in the reaction. The microsomal NADH-cytochrome b5 reductase activity was definitely low in the patient's thyroid. It was augmented to a normal level by incubation of the microsomes with FAD for 30 min or more. The activities of thyroid peroxidase, G6-PD, 6-PGD, catalase, protease, and NADPH-cytochrome c reductase were within normal limits. The major thyroid protein was normal thyroglobulin which could be readily iodinated in the presence of H2O2 and horse radish peroxidase. These findings suggest the correlation of an iodide organification defect with a cytochrome b5 reductase deficiency. Administration of high doses of FAD led to the restoration of thyroidal iodide organification mechanism associated with an increased thyroid hormone production and to a marked decrease of the goiter. Riboflavin was given without effect even at a high dosage level. Consequently, it seems likely that the deficient cytochrome b5 reductase activity in this patient is due to a defect in the biosynthesis of FAD, the coenzyme of the reductase, from riboflavin.
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PMID:Deficient cytochrome b5 reductase activity in nontoxic goiter with iodide organification defect. 116 26

t-Butyl hydroperoxide and H2O2-Fe(2+)-EDTA-glutathione system which produces hydroxyl radicals did not affect the 15-hydroxy prostaglandin dehydrogenase activity in rabbit kidney cortex. On the other hand, H2O2-Fe(2+)-EDTA-glutathione system inhibited the prostaglandin delta 13 reductase activity. Mannitol, a scavenger of hydroxyl radicals, had no effect on the inhibitory action of this system, indicating that the effect of H2O2-Fe(2+)-EDTA-glutathione system on the prostaglandin delta 13 reductase may not be due to produced hydroxyl radicals. As a result of further investigation, it was shown that glutathione disulfide, which is synthesized concomitantly with hydroxyl radicals from H2O2-Fe(2+)-EDTA-glutathione, inhibited the prostaglandin delta 13 reductase activity. These results suggest that hydroperoxides and hydroxyl radicals may not be likely candidates for the modulator of the catabolism of prostaglandins in the kidney cortex, and that glutathione disulfide has the potential to modulate the prostaglandin catabolism by affecting the prostaglandin delta 13 reductase activity.
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PMID:Inhibition of prostaglandin delta 13 reductase activity in rabbit kidney cortex by glutathione disulfide. 131 24

As oxidative stress has been implicated in the pathogenesis of certain viral diseases we determined antioxidant and prooxidant parameters in lungs and bronchoalveolar lavage fluid (BALF) of mice infected with a lethal dose of influenza A/PR8/34 virus. Viral infection was characterized by massive infiltration of leukocytes, mainly polymorphonuclear leukocytes, into the alveolar space. The total number of BALF cells increased up to 8-fold (day 3 post-infection) and these cells appeared activated as judged by their increased rates of superoxide anion radical (O2-.) generation upon stimulation. Maximal rates of radical generation by BALF cells during the early stages of infection were 15- or 70-fold higher than those of cells from control animals when expressed per cell or total BALF cells, respectively. At the terminal stages of infection the total capacity of BALF cells to release O2-. declined to approximately 35-fold the control values. Infection also resulted in increased in vivo formation of hydrogen peroxide (H2O2) within the lungs at a time that coincided with the maximal capacity of BALF cells to release O2-.. Whereas pulmonary activities of glutathione peroxidase and reductase remained unaltered, levels of ascorbate in the cell-free BALF decreased significantly during the early stages of the infection and then returned to normal levels and above, late in infection. The oxidation state of the dehydroascorbic acid/ascorbate couple increased concomitantly with the decrease in ascorbate concentrations early in infection and remained elevated throughout the infection. As assessed by the prevention of peroxyl radical-induced loss of phycoerythrin fluorescence, the total antioxidant capacity present in lung tissue homogenate from terminally ill animals was not diminished when compared to that prepared from lungs of control mice. We conclude that although early stages of influenza infection are associated with the presence of oxidative stress in the lung tissue and alveolar fluid lining the epithelial cells, this stress does not appear to overwhelm local antioxidant defenses. The results therefore do not support a direct causative role of oxidative tissue damage in the pathogenesis of influenza virus infection.
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PMID:Oxidative stress in lungs of mice infected with influenza A virus. 132 Oct 77

The soluble methane monooxygenase (MMO) system, consisting of reductase, component B, and hydroxylase (MMOH), catalyzes NADH and O2-dependent monooxygenation of many hydrocarbons. MMOH contains 2 mu-(H or R)oxo-bridged dinuclear iron clusters thought to be the sites of catalysis. Although rapid NADH-coupled turnover requires all three protein components, three less complex systems are also functional: System I, NADH, O2, reductase, and MMOH; System II, H2O2 and oxidized MMOH; System III, MMOH reduced nonenzymatically by 2e- and then exposed to O2 (single turnover). All three systems give the same products, suggesting a common reactive oxygen species. However, the distribution of products observed for most substrates that are hydroxylated in more than one position is different for each system. For several of these substrates, addition of component B to Systems I, II, or III causes the product distributions to shift dramatically. These shifts result in identical product distributions for Systems I and III in which MMOH passes through the 2e- reduced state ([Fe(II).Fe(II)]) during catalysis. In contrast, System II (in which MMOH probably does not become reduced) generally gives a unique product distribution. It is proposed that changes in MMOH structure occurring upon diiron cluster reduction and/or component complex formation cause substrates to be presented differently to the activated oxygen species. Kinetic studies show that component B strongly activates System I and, in most cases, strongly deactivates System II. The effect of component B on product distribution of System I (and III) occurs at less than 5% of the MMOH concentration, while nearly stoichiometric concentrations are required to maximize the rate of System I. This shows that component B has at least two roles in catalysis. EPR monitored titration of reduced MMOH ([Fe(II).Fe(II)]) with component B suggests that the effect of substoichiometric component B on product distribution is due to hysteresis in the MMOH conformational changes.
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PMID:Methane monooxygenase component B and reductase alter the regioselectivity of the hydroxylase component-catalyzed reactions. A novel role for protein-protein interactions in an oxygenase mechanism. 132 41

The thioredoxin/thioredoxin reductase system has been studied as regenerative machinery for proteins inactivated by oxidative stress in vitro and in cultured endothelial cells. Mammalian glyceraldehyde-3-phosphate dehydrogenase was used as the main model enzyme for monitoring the oxidative damage and the regeneration. Thioredoxin and its reductase purified from bovine liver were used as the regenerating system. The physiological concentrations (2-14 microM) of reduced thioredoxin, with 0.125 microM thioredoxin reductase and 0.25 mM NADPH, regenerated H2O2-inactivated glyceraldehyde-3-phosphate dehydrogenase and other mammalian enzymes almost completely within 20 min at 37 degrees C. Although the treatment of endothelial cells with 0.2-12 mM H2O2 for 5 min resulted in a marked decrease in the activity of glyceraldehyde-3-phosphate dehydrogenase, it had no effect on the activities of thioredoxin and thioredoxin reductase. Essentially all of the thioredoxin in endothelial cells at control state was in the reduced form and 70-85% remained in the reduced form even after the H2O2 treatment. The inactivated glyceraldehyde-3-phosphate dehydrogenase in a cell lysate prepared from the H2O2-treated endothelial cells was regenerated by incubating the lysate with 3 mM NADPH at 37 degrees C and the antiserum raised against bovine liver thioredoxin inhibited the regeneration. The inhibition of thioredoxin reductase activity by 13-cis-retinoic acid resulted in a decrease in the regeneration of glyceraldehyde-3-phosphate dehydrogenase in the H2O2-treated endothelial cells. The present findings provide evidence that thioredoxin is involved in the regeneration of proteins inactivated by oxidative stress in endothelial cells.
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PMID:Thioredoxin regenerates proteins inactivated by oxidative stress in endothelial cells. 142 98

Contents of hepatic microsomal protein, aminopyrine N-demethylase, acetanilide hydroxylase, aniline hydroxylase, hydrogen peroxide formation, cytochrome-c-reductase, cytochrome b5 and cytochrome P-450 were examined in control, phenobarbital (PB), 3-methylcholanthrene (3-MC) and 1, 1, 1-trichloro-2, 2-bis(p-chlorophenyl)ethane (DDT) treated group of 1-28 days old chickens. Increase in aminopyrine N-demethylase, acetanilide hydroxylase, aniline hydroxylase, cytochrome-c-reductase, cytochrome b5 and cytochrome P-450 was noticed at all stages of development during administration of PB and 3-MC. But these enzyme activities were not always paralleled by increase in age. Aminopyrine N-demethylase was increased in early stages only during DDT administration, which indicates that the form of cytochrome P-450, responsible for aminopyrine N-demethylation is present in early stages only. However, acetanilide hydroxylase was decreased in all stages of development, in postnatal development the basal activities of the enzymes for various substrates do not exhibit identical pattern, the degree of inducibility by inducers varied in relation to age of animal. Hydrogen peroxide formation increased in all stages of developing chickens due to the administration of PB and DDT. It however decreased due to 3-MC administration which may be due to induction of high spin cytochrome P-450.
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PMID:Hepatic mixed function oxidase system and effect of phenobarbital, 3-methylcholanthrene and 1, 1, 1-trichloro-2, 2-bis(p-chlorophenyl)ethane in developing chickens. 145 19

Glycerol can be oxidized by rat liver microsomes to formaldehyde in a reaction that requires the production of reactive oxygen intermediates. Studies with inhibitors, antibodies, and reconstituted systems with purified cytochrome P4502E1 were carried out to evaluate whether P450 was required for glycerol oxidation. A purified system containing phospholipid, NADPH-cytochrome P450 reductase, P4502E1, and NADPH oxidized glycerol to formaldehyde. Formaldehyde production was dependent on NADPH, reductase, and P450, but not phospholipid. Formaldehyde production was inhibited by substrates and ligands for P4502E1, as well as by anti-pyrazole P4502E1 IgG. The oxidation of glycerol by the reconstituted system was sensitive to catalase, desferrioxamine, and EDTA but not to superoxide dismutase or mannitol, indicating a role for H2O2 plus non-heme iron, but not superoxide or hydroxyl radical in the overall glycerol oxidation pathway. The requirement for reactive oxygen intermediates for glycerol oxidation is in contrast to the oxidation of typical substrates for P450. In microsomes from pyrazole-treated, but not phenobarbital-treated rats, glycerol oxidation was inhibited by anti-pyrazole P450 IgG, anti-hamster ethanol-induced P450 IgG, and monoclonal antibody to ethanol-induced P450, although to a lesser extent than inhibition of dimethylnitrosamine oxidation. Anti-rabbit P4503a IgG did not inhibit glycerol oxidation at concentrations that inhibited oxidation of dimethylnitrosamine. Inhibition of glycerol oxidation by antibodies and by aminotriazole and miconazole was closely associated with inhibition of H2O2 production. These results indicate that P450 is required for glycerol oxidation to formaldehyde; however, glycerol is not a direct substrate for oxidation to formaldehyde by P450 but is a substrate for an oxidant derived from interaction of iron with H2O2 generated by cytochrome P450.
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PMID:Role of cytochrome P450 in the oxidation of glycerol by reconstituted systems and microsomes. 153 67


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