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 complete amino acid sequence of a hemoglobin from yeast (Candida norvegensis) has been determined by peptide and cDNA sequence analyses. The protein is composed of 387 amino acid residues and its amino terminus was blocked by an acetyl group. A computer search showed that the sequence of 155 N-terminal residues has 39% homology with that of Vitreoscilla hemoglobin. On the other hand, the sequence of 230 C-terminal residues showed a small, but notable, degree of similarity with that of a methemoglobin reductase found in human erythrocyte, i.e. NADH-cytochrome b5 oxido-reductase. We therefore conclude that yeast hemoglobin consists of two distinct domains; one is a heme-containing oxygen binding domain of the N-terminal region and the other is an FAD-containing reductase domain found in the C-terminal region.
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PMID:Amino acid sequence of yeast hemoglobin. A two-domain structure. 140 99

It is found that nitrite-ions formed as a result of biotransformation during long term feeding of calves with sodium and potassium nitrates induce changes in some biochemical parameters of blood, including HS-glutathione content in erythrocytes, acid hemolytic resistance of erythrocytes, activity of NAD-dependent methemoglobin-reductase, correlation of ligand forms of hemoglobin and its total content. It is supposed that the observed changes are of an adaptational character and, as a whole, provide for the optimization of both quantitative and qualitative composition of population of erythroid cells at the expense of erythropoiesis intensification.
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PMID:[Ligand spectrum of hemoglobin activity of methemoglobin-reductase and hemolytic resistance of erythrocytes during chronic exposure to nitrates]. 144 77

Amino derivatives of ortho-benzoquinone (OBQ) were demonstrated to have a protective action in acute toxic hemic hypoxia induced by sodium nitrite given to laboratory animals. This action of OBQ was due to its capacity to activate the recovery of blood oxygen transport function by accelerating the restoration of methemoglobin and determined by their electron-acceptor properties, lipophilicity and NADP-dependent methemoglobin reductase affinity.
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PMID:[A comparative study of the activity of antihypoxic agents in hemic hypoxia]. 145 86

In conclusion, many specialized tests for the evaluation of anemia and RBC abnormalities can readily be performed in-house or by commercial laboratories. Tests include RBC indices, examination of blood smears (for morphological changes, infectious agents, basophilic stippling, and polychromasia), reticulocyte counts, iron stains, serum iron determinations, Heinz body counts, and methemoglobin tests. These diagnostic tests should routinely be used for the evaluation of hematologic abnormalities that are detected by a CBC. Accurate interpretation of test results will provide vital information on the pathophysiological and/or etiologic mechanisms of disease and point the way to successful therapeutic intervention. Failure to adequately resolve some hematologic abnormalities, particularly in breeds in which heritable disease is a consideration, may require additional tests, including serum haptoglobin, ferritin and erythropoietin measurement, or assays for RBC enzymes, such as methemoglobin reductase, PK, and PFK. These tests usually are available only through research laboratories or hematology specialists, and it is advisable to consult with a veterinary clinical pathologist for referral to the appropriate individual or laboratory.
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PMID:Specialized hematology tests. 147 Jul 72

Acquired methemoglobinemia results from the exposure to various chemicals and drugs able to oxidize hemoglobin at a rate exceeding the normal enzymatic capacity for hemoglobin reduction. Levels of methemoglobin exceeding 60-70% may be associated with coma and death. We describe a case of complete, uneventful recovery involving a 10 week-old infant who presented to the Emergency Department with profound sudden onset of cyanosis, irritability, metabolic acidosis, and a lethal methemoglobin level of 71.4%. Intravenous administration of 12 mg methylene blue resulted in immediate resolution of the cyanosis and reduction of measured methemoglobin to 1.3%. The carboxyhemoglobin was negative. Sodium bicarbonate successfully corrected the acidosis. RBC reductase measurement was within normal limits, ruling out congenital methemoglobinemia. Family history revealed a wood-burning stove which emitted pine tar fumes as the potential environmental methemoglobin-producing source. The infant's cradle was situated five feet from the stove. The infant was discharged on day three of hospitalization with a methemoglobin level of 0.2%.
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PMID:Environmentally-induced methemoglobinemia in an infant. 154 42

An NADPH-dependent reductase, first shown in the 1930s to catalyze the methylene blue-dependent reduction of methemoglobin in erythrocytes, has now been characterized as a high-affinity heme-binding protein and has been detected in liver. Highly purified bovine erythrocyte reductase binds protohemin to form a 1:1 complex with a Kd of 7 nM. Binding of protohemin completely inhibits reductase activity. Other tetrapyrroles and fatty acids also bind to the reductase and inhibit its activity. Protoporphyrin, hematoporphyrin, and coproporphyrin form 1:1 complexes with Kd values ranging from 1 to 5 microM. The inhibition constants for a number of saturated and unsaturated fatty acids range from 6 to 52 microM. A protein that is immunologically cross-reactive to the reductase has been detected in the cytosolic fractions of bovine and rat liver and of bovine, rat, rabbit, and human erythrocytes. By immunoblot analysis, the bovine liver and erythrocyte proteins appear identical in size, as do the rat liver and erythrocyte proteins. The concentration of the protein in bovine erythrocytes has been estimated by quantitative immunoblotting to be 10 microM. The detection of this protein in liver cells, the demonstration of its binding properties, and its weak reductase activity bring into question the long-held belief that this is uniquely an erythrocyte protein and that it functions as a reductase.
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PMID:Characterization of NADPH-dependent methemoglobin reductase as a heme-binding protein present in erythrocytes and liver. 154 73

Clinical efficacy of two pretreatment regimens, sodium nitrite (SN) + hydroxylamine (HA) and SN + 4-dimethylaminophenol (DMAP) were evaluated in rats by studying various biochemical variables at different time intervals. Animals given single subcutaneous (s.c.) co-administration of SN+HA or SN+DMAP showed significantly elevated levels of blood bilirubin indicating hemolytic anemia. Increased levels of blood creatine phosphokinase (CPK), lactate dehydrogenase (LDH) and glutamic oxaloacetic transaminase (GOT) were indicative of aseptic necrosis at the injection site. On account of low methemoglobin reductase activity in human erythrocytes, a reduced sub-clinical dose of HA or DMAP is envisaged in humans.
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PMID:Biochemical changes induced by two new prophylactic regimens for cyanide antagonism. 161 Mar 71

A total of 440 clinically normal children aged from 1 month to 1 year, whose parents are indigenes of the Zabaikalye, were investigated to elucidate the influence of the climatic conditions of the Zabaikalye on the erythrocytic system state. It has been found that the total number of red blood cells, the mean volume of cells containing fetal hemoglobin and methemoglobin, and the number of highly-resistant, i.e. young, red cells, are increased in the children of the Zabaikalye, as compared to those living under conditions of a moderate climate. Methemoglobin reductase activity in them is decreased. The data obtained have evidenced that under conditions of chronic hypoxia erythropoiesis in children living in the Zabaikalye is in the state of high tension.
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PMID:[The main indicators of the erythrocyte system in infants in the Baikal region]. 169 8

Red blood cell cytosol promotes enzymic N-demethylation reactions which display typical Michaelis-Menten kinetics with respect to N-methylaniline as substrate. The demethylase activity is linked with hemoglobin (Hb) and is enhanced in the presence of NADH and the NADH-methemoglobin reductase system. It has been adduced that Hb in its oxygenated form is involved in the reaction.
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PMID:Enzymic N-demethylation reaction catalysed by red blood cell cytosol. 173 9

Sodium nitrite induced poisoning resulted into oxidation-reduction disorders with concomitant changes in the ratio of the oxidated and reduced forms towards accumulation of the oxidated equivalents. Antioxidants unithiol, tocopherol acetate, ascorbic acid, methylene blue, violuric acid influenced the oxidation-reduction balance in different ways. The protective action of violuric acid was comparable with that of methylene blue and exceeded the unithiol protective properties. Violuric acid, as compared with unithiol, ascorbic acid and tocopherol, was more effective in decreasing methemoglobin and nitrates contents in blood in methemoglobinemia cases. The violuric acid and methylene blue protective mechanisms are in all probability influenced by the antioxidant properties of these substances and their reductase activity.
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PMID:[Protective effect of antioxidants in methemoglobinemia caused by sodium nitrite in experimental studies]. 179 97


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