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 reduction of hemoglobins (Hb) M such as Hb M Iwate, Hb M Boston, Hb M Hyde Park, Hb M Saskatoon, and Hb M Milwaukee by the ferredoxin and ferredoxin-NADP reductase system was studied systematically under anaerobic conditions. The enzyme system could not reduce the abnormal chains in methemoglobin M with an alpha chain anomaly but effectively converted the methemoglobin M with a beta chain anomaly to the fully reduced form. During the reduction of the methemoglobin M with a beta chain anomaly, the spectra showed a shift of the initial isosbestic points, indicating the possible formation of intermediate hemoglobins in the partially reduced state. On the reduction mode of the methemoglobin M, however, it was classified into three types. 1) Only normal chains were reduced (Hb M Iwate and Hb M Boston). 2) Sequential reduction from normal to abnormal chains occurred (Hb M Milwaukee and Hb M Hyde Park). 3) Normal chains were preferentially reduced, but the reduction of abnormal chains also started at the same rate when the reduction of normal ones had proceeded halfway (Hb M Saskatoon). These differences are discussed in relation to the redox potential of each abnormal chain in methemoglobin M.
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PMID:Reduction of methemoglobins M Hyde Park, M Saskatoon, and M Milwaukee by ferredoxin and ferredoxin-nicotinamide adenine dinucleotide phosphate reductase system. 664 89

The ATP-dependent proteolytic system present in reticulocytes can release the active hydrophilic domain of cytochrome b5 and NADH-cytochrome b5 reductase from the endoplasmic reticulum, that in mature erythrocytes act as methemoglobin reductase.
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PMID:The possible role of ATP-dependent proteolysis on the solubilization of methemoglobin reductase during reticulocyte maturation. 665 16

Reductions of five species of hemoglobins (Hb1) M by two methemoglobin reductases and by ferredoxin and ferredoxin-NADP reductase were studied under anaerobic conditions. Abnormal chains of Hb M Milwaukee and Hb M Saskatoon were reduced by NADH-cytochrome b5 reductase (= NADH-methemoglobin reductase) highly purified from human erythrocytes. Hb M Saskatoon was also reduced by an another enzyme in red cells, NADPH-flavin reductase (= NADPH-methemoglobin reductase). All Hbs M with a beta chains anomaly such as Hb M Hyde Park, Hb M Saskatoon, and Hb M Milwaukee were reduced by ferredoxin and ferredoxin-NADP reductase. These three enzymatic reduction systems did not reduce Hbs M with an alpha chain anomaly such as Hb M Iwate and Hb M Boston. These differences in the reduction are discussed in relation to the redox potential of each abnormal chain in methemoglobin M.
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PMID:Enzymatic reduction of hemoglobins M. 667 86

Methemoglobin formation in the presence of acetylphenyl hydrazine occurs faster in red cells from cord blood than in normal adult erythrocytes. Under the same conditions, the rate of disappearance of glutathione is slower in cord blood erythrocytes. The mean NADH-methemoglobin reductase activity of cord blood red cells is less than half of the adult value. The results point to a potential danger in the administration of oxidant drugs to expectant mothers or new-born infants.
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PMID:Methemoglobin formation and glutathione disappearance in cord blood red cells exposed to acetylphenylhydrazine. 672 57

Acetaminophen (APAP) was given orally to 6 mature cats (3 male and 3 female) in single progressive doses of 20 (low), 60 (medium), or 120 (high) mg APAP/kg body weight, each 3 weeks apart. Methemoglobin (MHB), reduced blood glutathione (GSH) and APAP blood concentrations, and blood NADH methemoglobin reductase and NADPH glutathione reductase activities were measured periodically for 8 days after dosing. A statistically significant increase in MHB formation (21.7% and 45.5%, respectively) occurred following the medium and high doses. NADH methemoglobin reductase activity at the high dose decreased significantly. Red blood cell GSH concentrations decreased significantly during the first 24 h after the high APAP dose and returned to normal by 192 h. NADPH glutathione reductase activity decreased significantly following the high dose, but not after the lower APAP doses.
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PMID:The effect of acetaminophen on methemoglobin and blood glutathione parameters in the cat. 674 Jul 6

Methemoglobinemia and hemolysis are well-known side effects after using high doses of dapsone (4,4'-diaminodiphenylsulfone). Their occurrence after low doses of the drug, and subsequent investigation, revealed the presence of hemoglobin Hasharon, and low content of NADH-dependent methemoglobin reductase in five members of an East European ashkenazic Jewish family.
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PMID:Dapsone-induced methemoglobinemia and hemolysis in the presence of familial hemoglobinopathy Hasharon and familial methemoglobin reductase deficiency. 676 4

The problem of the low activity of so-called methemoglobin reductase in red cells from newborns was reinvestigated in view of our current knowledge of this enzyme, i.e., (1) its being cytochrome-b5 reductase and (2) its presence in two forms: soluble and membrane-bound. We found that red cells from cord blood and newborns exhibited a 50% decrease of soluble cytochrome-b5 reductase activity, whereas membrane-bound activity was in the adult range. Ghosts from these cells possessed diminished ability to solubilize membrane-bound cytochrome-b5 reductase in the course of in vitro auto-incubation. This autosolubilizing ability increased with age and reached adult level concomitantly with soluble cytochrome-b5 reductase activity at 6 mo. We conclude that the relative deficiency of soluble cytochrome-b5 reductase observed at birth is due to diminished post-translational processing of the membrane-bound enzyme during erythropoiesis of fetal cells. This processing is calcium-dependent related to calmodulin.
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PMID:Endogenous proteolysis of membrane-bound red cell cytochrome-b5 reductase in adults and newborns: its possible relevance to the generation of the soluble "methemoglobin reductase". 683 Oct 51

The purification and properties of metlegoglobin reductase from lupine (Lupinus luteus L.) nodules are described. The purification procedure results in a 1056-fold purification of the enzyme with a total yield of 21%. The enzyme possesses the NADH-diaphorase activity. Metlegoglobin reductase is heterogenous during electrophoresis and isoelectric focusing. Electrophoresis produces two vicinal active bands, while isoelectrofocusing results in four active fractions. The fraction possessing the highest activity has a pI of 4.4. The enzyme is a flavoprotein, in which all flavins are represented by FAD. The molecular weight of the enzyme is 30 000. In some properties metlegoglobin reductase from lupine nodules is similar to methemoglobin reductase from erythrocytes and metmyoglobin reductase from muscles.
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PMID:[Properties of metlegoglobin reductase from lupine nodules]. 689 54

The biochemical processes involved in the formation of methemoglobin, in the protection of hemoglobin against oxidation to methemoglobin, and in the reduction of methemoglobin to hemoglobin are reviewed. Special emphasis is directed to the major and minor metabolic pathways in human erythrocytes that are involved in the reduction of methemoglobin, and evidence is presented that the NADH-methemoglobin reductase system, involving a soluble cytochrome b5 and NADH-cytochrome b5 reductase, it is the most important reductive mechanism. Toxic methemoglobinemia, methemoglobinemia due to hemoglobin M's, and hereditary methemoglobinemia due to deficiency in NADH-methemoglobin reductase activity are considered. Their clinical manifestations, diagnosis, and treatment are discussed briefly.
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PMID:Methemoglobin pathophysiology. 702 66

Because cobalt compounds tend to form stable complexes, there has been continued interest in the use of the salts and chelates of cobalt in cyanide poisoning, and continued uncertainty about the precise nature of their protective effects. We have found that cobalt ions inhibit the enzymatic reduction of both methemoglobin and metmyoglobin. Virtually total inhibition of methemoglobin and metmyoglobin reductase activity occurred with the addition of 2.5 mM cobalt acetate to the assay system. Both enzymes were inhibited by lower levels of cobalt in a dose-dependent manner. The similarity in susceptibility of cobalt inhibition is further evidence that the enzymes which reduce methemoglobin and metmyoglobin are functionally comparable. The inhibition of methemoglobin reductase activity may be, in part, responsible for the therapeutic effectiveness of cobalt salts and chelates in cyanide poisoning.
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PMID:Inhibition of methemoglobin and metmyoglobin reduction by cobalt. 710 39


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