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)

Methods have been developed for the purification of eight rat liver microsomal cytochrome P-450 (P-450) isoenzymes. Another rat P-450, responsible for the metabolism of the genetic polymorphism prototype debrisoquine, has also been partially purified from rat liver. Six P-450s have been purified to electrophoretic homogeneity from human liver preparations. The rat and human P-450s can be quantified in crude samples using 'immunoblotting' methods coupled with peroxidase visualization. A study on the effects of a family of polybrominated biphenyl congeners led to the conclusion that the levels of all of the rat P-450s considered above are under some degree of independent regulation. In monolayer culture, different P-450s show different stabilities and levels of several are selectively regulated by various media components. Studies with the eight isolated rat P-450s indicate that the iron spin state, oxidation-reduction potential (Fe3+/Fe2+ couple), and catalytic activity towards substrates are not related to each other. The major function of phospholipid in reconstituted P-450/NADPH-P-450 reductase systems is the facilitation of formation of a complex of the two proteins. Studies on the regioselective hydroxylation of warfarin have been used to develop an order of binding affinity of the different P-450s for NADPH-P-450 reductase.
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PMID:Factors involved in the regulation of the levels and activities of rat liver cytochromes P-450. 642 22

Incubation of rat liver cell-free extracts with an NADPH-generating system and with nifurtimox or benznidazole (two nitroheterocyclic drugs used in the treatment of Chagas' disease) produced oxidation of reduced glutathione (GSH) and increased lipid peroxidation, as shown by the generation of thiobarbituric-acid-reacting intermediates. Nifurtimox and benznidazole inhibited GSSG-reductase, but not GSH-peroxidase, the former inhibition contributing to GSH depletion. In every case, nifurtimox was more effective than benznidazole. Addition of GSH or free-radical scavengers (catalase, superoxide dismutase, mannitol, sodium benzoate or L-histidine) prevented the effect of nifurtimox on lipid peroxidation reactions. These results support the assumption [M. Dubin, S. N. J. Moreno, E. E. Martino, R. Docampo and A. O. M. Dubin, Biochem. Pharmac. 32, 483 (1983)] that, in the rat liver, GSH exerts a protective action against oxygen radicals generated by the nitroheterocyclic drugs.
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PMID:Effect of nitroheterocyclic drugs on lipid peroxidation and glutathione content in rat liver extracts. 649 1

Phenazine methosulfate (PMS) has been successfully used to mediate electron transfer from NADH to cytochrome P-450-CAM in the absence of putidaredoxin and putidaredoxin reductase under aerobic conditions. Identification and quantitation of exo-5- hydroxycamphor , the only product, has been accomplished by gas chromatography. In the absence of cytochrome P-450-CAM, or when other heme proteins (hemoglobin, myoglobin, horseradish peroxidase) are substituted for P-450-CAM, no exo-5- hydroxycamphor is detected. Product formation is not inhibited by the addition of catalase, superoxide dismutase, or hydroxyl radical scavengers; however, significant inhibition is observed with carbon monoxide and metyrapone, known inhibitors of the fully reconstituted P-450 system. Addition of 2,3-dimercaptopropanol to the NADH/PMS/P-450 system leads to a 4-fold increase in product formation; when putidaredoxin is added (without dimercaptopropanol), a 20-fold increase in product formation is observed. Constant bubbling with oxygen results in a further increase in the amount of product (150-fold increase overall). Our results show that PMS can substitute for the electron-transfer proteins putidaredoxin and putidaredoxin reductase in the transfer of electrons from NADH to P-450-CAM, resulting in multiple turnovers. Molecular oxygen dependent multiple turnovers of cytochrome P-450 have not been previously observed without the fully reconstituted, three-protein system.
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PMID:NADH- and oxygen-dependent multiple turnovers of cytochrome P-450-CAM without putidaredoxin and putidaredoxin reductase. 672 35

A NADPH-dependent t-butyl hydroperoxide ( TBH )-reducing activity independent of glutathione was found in addition to glutathione peroxidase activity bound to erythrocyte membranes. In "hypotonic" and "isotonic" membranes the NADPH-dependent TBH -reducing activity amounted to about 0.34 mu kat /l red blood cells (RBC) and the glutathione peroxidase activity to 0.32 mu kat /l RBC. The activities do not appear to be additive. The membrane association of the enzymes is independent of ionic strength. Under hypotonic condition about 0.2% of the total cellular catalase activity were bound to the membrane but none in "isotonic" membranes. The bound catalase appears to exhibit a glutathione dependent peroxidase activity. Membrane-bound haemoglobin exhibited a quasi- TBH -reductase activity which was inhibited by azide and cyanide.
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PMID:Enzymatic t-butyl hydroperoxide reduction on human erythrocyte membranes--NADPH and GSH dependent activities. 674 3

An autopsy case of a 73-year-old man with "black thyroid" was reported. Investigations by light and electron microscopy and histochemical study of the black thyroid material disclosed the massive deposition brown granules in the follicular cells, to be residual bodies containing lipids. Lipids in these granules were mainly composed of phospholipid by biochemical analysis. Concerning the thyroidal function of this case the value of T4-I in the serum was within normal range (4.8-7.5 micrograms/dl) and peroxidase, NADPH-cytochrome C reductase and acid phosphatase activity in the black thyroid material revealed no significant increase or decrease, compared with other 12 autopsied cases. These granules resembled so-called lipofuscin granules, and the frequency and grade of the deposition in autopsied cases increase with aging.
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PMID:Black thyroid. Morphological, biochemical and geriatric studies on the brown granules in the thyroid follicular cells. 680 14

Pretreatment with cycloheximide or emetine provided significant protection against pulmonary edema in rats exposed to ozone or nitrogen dioxide. Other inhibitors of protein-synthesis, actinomycin D or puromycin, failed to show such effects. Possible actions of these agents as well as the doses and times that afforded the significant protection were investigated. These agents, by themselves, did not alter the water content of the lungs. In vitro study revealed that both cycloheximide and emetine hardly acted as scavengers of oxidant. Pretreatment with either agent was associated with a significant increase in the activity of glucose 6-phosphate dehydrogenase of the lungs, but the increase did not necessarily coincide with the protection. Activity levels of non-protein SH, glutathione-peroxidase and -reductase in the lungs of rats treated with either agent were scarcely altered. The effect of these agents administered in vivo or in vitro on the in vitro lipid peroxidation by air was also investigated. Other possible mechanisms of these agents responsible for the protective effect against pulmonary edema induced by oxidants were also discussed.
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PMID:Protection with cycloheximide or emetine against pulmonary edema induced by ozone or nitrogen dioxide. 713 93

Human erythrocytes were separated into three groups according to their density and age by centrifugation in a continuous Percoll gradient. The specific activities of glucose-6-phosphate dehydrogenase, catalase, glutathione peroxidase, glutathione reductases as well as the glutathione and selenium content were highest in the youngest cell and uniformly decreased by about 20-30% in the eldest group. The age-dependence of superoxide dismutase was much more pronounced. The malondialdehyde content taken as an estimate for lipid peroxidation showed an inverse age dependence and increased by 35% in the eldest cell population. Red blood cells from 10 anemic patients exhibited less glutathione and also less malondialdehyde, while GSH-peroxidase and GSSG-reductase contents were higher. The parameters showed similar age profiles as in healthy subjects. The findings support the concept of lipid peroxidation as one of the causal events in red cell aging, but do not allow to deduce the involvement of a single enzyme related to the glutathione redox cycle in this process.
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PMID:[Activity of the glutathione redox system in human erythrocytes at various ages]. 713 38

Depletion of hepatic glutathione (GSH) in phenobarbital-induced rats by phorone (diisopropylidene acetone; 0.25 g/kg i.p.) or vinylidene chloride (VDC; 0.5 g/kg i.p.) led to an enhanced lipid peroxidation in vitro as evidenced by the measurements of malondialdehyde and conjugated dienes. During this state of GSH-depletion inducing lipid peroxidation no significant alterations in the activity of hepatic GSH-peroxidase were observed whereas the GSH-S-transferase activities towards an aryl substrate (CDNB) and an epoxide substrate (1,2-epoxy(p-nitrophenoxy)propane) significantly decreased under the treatments with VDC. The GSH-reductase activity was significantly reduced after treatment with either agent. These results clearly indicate 1st, that GSH-S-transferases are involved in the conjugation of GSH to VDC, 2nd, that GSH peroxidase remains unaffected during lipid peroxidation induced by GSH-depletion as a consequence of treatment with phorone or VDC, and 3rd, that the availability of reduced GSH may be decreased further under these conditions due to the lower content of glutathione reductase.
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PMID:Glutathione-S-transferase and GSH-peroxidase activities during the state of GSH-depletion leading to lipid peroxidation in rat liver. 713 25

Benzophenone-3 (BZ-3) is a category 1 (over-the-counter) product approved by the US Food and Drug Administration (FDA) for use as a sunscreen agent in medicine, cosmetics, industry, and agriculture. This is due to its ability to absorb and dissipate ultraviolet light in a harmless manner, thus protecting human skin and products from UV irradiation. This study investigated the safety of BZ-3 after repeated administration. BZ-3 in ointment base was applied at a dose of 100 mg/kg body wt. twice daily, for 4 weeks to the skin of male Sprague-Dawley rats. Body weight, organ to body weight ratios, hematological, and clinical chemistry parameters were not effected. Pathological examination revealed no significant changes between control and treated animals. No gross external abnormalities were observed. Both in vivo and in vitro blood glutathione (GSH) levels were effected by BZ-3 treatment. However, after 60 min of incubation, a reversal of this effect was observed in the treatment group as blood GSH levels approached normal levels. Furthermore, investigation of GSH-reductase and peroxidase with time indicated an increase in GSH-reductase activity at 60 and 90 min with no effect on GSH-peroxidase. Pre-treatment with phenobarbital modulated the metabolic disposition of BZ-3. There was an increase in the formation of the hydroxy metabolites but not the O-dealkylated form. This study suggests that BZ-3 is not toxic to rats when applied dermally at a dose of 100 mg/kg body wt. for 4 weeks.
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PMID:Safety evaluation of benzophenone-3 after dermal administration in rats. 748 93

Three different molecular masses (24, 22, and 20 kDa) of antioxidant proteins were purified in Escherichia coli. These proteins exhibited the preventive effects against the inactivation of glutamine synthetase activity and the cleavage of DNA by a metal-catalyzed oxidation system capable of generating reactive oxygen species. Their antioxidant activities were supported by a thiol-reducing equivalent such as dithiothreitol. Analysis of the amino-terminal amino acid sequences and the immunoblots between 24- and 22-kDa proteins indicates that the 24-kDa protein is an intact form of the 22-kDa protein that was previously identified 22-kDa subunit (AhpC) of E. coli alkyl hydroperoxide reductase (AhpC/AhpF). We isolated and sequenced an E. coli genomic DNA fragment that encodes 20-kDa protein. Comparison of the deduced amino acid sequence of the 20-kDa protein with that of AhpC revealed no sequence homology. A search of a data bank showed that the 20-kDa protein is a new type of antioxidant enzyme. The synthesis of this novel 20-kDa protein was increased in response to oxygen stress during growth. The 20-kDa protein resides mainly in the periplasmic space of E. coli, whereas the 24-kDa AhpC resides mainly in the matrix. The 20-kDa protein was functionally linked to the thioredoxin as an in vivo thiol-regenerating system and exerted a peroxidase activity. This 20-kDa protein is thus named "thiol peroxidase," which could act as an antioxidant enzyme removing peroxides or H2O2 within the catalase- and peroxidase-deficient periplasmic space of E. coli.
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PMID:Thioredoxin-linked "thiol peroxidase" from periplasmic space of Escherichia coli. 749 81


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