Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.8.1.4 (diaphorase)
 2,754 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The organic phosphate allosteric effectors of hemoglobin, inositol hexaphosphate, 2,3-diphosphoglycerate, and ATP, interact with NADH-methemoglobin reductase (NADH-diaphorase). Significant inhibitory effects on the enzyme were found when dichlorophenolindophenol, or ferricyanide were used as electron acceptors in place of methemoglobin. In contrast, apparent stimulation of enzyme activity was observed when adult human methemoglobin was used as the electroganic phosphate on the rate of reaction due to its interaction with the substrate methemoglobin to produce the favored T type of quaternary conformation. The inhibitory effect of inositol hexaphosphate on the enzyme is associated with a perturbation in the reactivity of essential sulfhydryl group(s) on the enzyme. It is suggested that the interaction of the organic phosphate with the enzyme as well as with the substrate is significant in determining the overall rate of methemoglobin reduction.
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PMID:Inhibition of NADH-methemoglobin reductase by organic phosphates. 49 34

Erythrocytic NADH methemoglobin diaphorase acquires NADH-dichlorophenolindophenol diaphorase activity when enzyme-associated NAD is removed. This transformation is reversible and can be mediated by membrane NAD glycohydrolase (EC 3.2.2.5) in hemolysates as well as in intact cells exposed to hydrogen peroxide. It is abolished either in NADH methemoglobin diaphorase deficiency or in NAD(P) glycohydrolase (EC 3.2.2.6) deficiency which is common in Afro-American but not in European-American adults. Activities of erythrocytic NADP glycohydrolase and NAD glycohydrolase appear to depend on a single membrane enzyme.
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PMID:NAD(P) glycohydrolase deficiency in human erythrocytes and alteration of cytosol NADH-methemoglobin diaphorase by membrane NAD-glycohydrolase activity. 436 76

Hemin degradation was observed in the presence of NADH and lipoamide dehydrogenase at pH 6.5-9.0. The degradation was inhibited by 80% by catalase and by 70% by superoxide dismutase. This system oxidized oxyhemoglobin to methemoglobin but only slightly degraded heme in hemoglobin.
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PMID:Heme degradation with participation of the superoxide radical in the presence of NADH and lipoamide dehydrogenase. 609 53

Human placenta contains a thermostable, cytosolic NADH-diaphorase which is different from the other diaphorases and which we designate as diaphorase P. It is specific for NADH and reduces artificial substrates such as dichlorophenol and tetrazolium derivatives, but not natural substrates such as methemoglobin, cytochrome b5 or lipoate. It is antigenically distinct from the ubiquitous red-cell type NADH-diaphorase (soluble cytochrome b5 reductase) specified by the DIA1 locus. Using electrophoretic and immunologic methods, it was possible to detect diaphorase P in various fetal tissues (brain, liver, kidney, muscle), whereas was not found in adult tissues with the exception of the brain. This enzyme, the physiological role of which remains unknown, appears to belong, therefore, to the category of fetal proteins. Its resurgance in primary liver cancer was demonstrated in three cases.
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PMID:Diaphorase P: a new fetal isozyme identified in human placenta. 624 54

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

Dihydrolipoamide dehydrogenase (DLDH; EC 1.8.1.4) from porcine heart is capable of using nitric oxide (NO) as an electron acceptor, with NADH as the electron donor, forming nitrate in the reaction. NADPH was not effective as an electron donor. The reaction had a pH optimum near 6 and was not inhibited by cyanide or diphenyleneiodonium ions. The Km for NADH was 10 microM, while that for NO was 0.5 microM. The rate of NO conversion was comparable to the rate of lipoamide conversion (200 micromol min(-1) mg(-1) protein at pH 6). Cytochrome c or myoglobin were poor electron acceptors by themselves but, in the presence of methylene blue, DLDH had an activity of 5-7 micromol min(-1) mg(-1) protein with these substrates, indicating that DLDH can act also as a methemoglobin reductase. While the Km of DLDH for NO is relatively low, it is in the physiological range of NO levels encountered in the tissue. The enzyme may, therefore, have a significant role in modifying NO levels under specific cell conditions.
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PMID:Dihydrolipoamide dehydrogenase from porcine heart catalyzes NADH-dependent scavenging of nitric oxide. 1519 36