NADH-methemoglobin reductase

The methemoglobin formed is reduced back to hemoglobin through the action of NADH-methemogtobin reductase (reaction ). A smaller fraction of the methemoglobin is reduced by a similar enzyme requiring NADPH (as indicated by the colored arrow). A hereditary lack of the NADH-methemoglobin reductase is also known. 

NADH-methemoglobin reductase 826 NADH ubiquinone oxidoreductase 788 oxidation by ferricyanide 780 NADP+ (NADP) 507, 765 - 771, 767s, 779 in catalase 853 isolation of 767... 

Topical administration of lidocaine to the nasal mucosa occasionally causes severe methemoglobinemia in patients who have the heterozygous form of NADH methemoglobin reductase deficiency (63). 

Methemoglobinemia has been reported with benzocaine, Cetacaine (a mixture of benzocaine, butyl aminobenzo-ate, and tetracaine), cocaine, lidocaine, novocaine, and prUocaine. Acquired methemoglobinemia can result from exposure to chemicals that contain an aniline group, such as benzocaine and procaine, or to those that are transformed to metabolites that contain an aniline group, such as lidocaine and prilocaine. Toxic blood concentrations of local anesthetics, aberrant hemoglobin, and NADH-methemoglobin reductase deficiency are critical... 

Hsieh, H.-S., and Jaffe, E. R., 1971, Electrophoretic and functional variants of NADH-methemoglobin reductase in hereditary methemoglobinemia, /. Clin. Invest. 50 196. 

Methemoglobinemia Intake of excess oxidants (various chemicals and drugs) Genetic deficiency in the NADH-dependent methemoglobin reductase system (MIM 250800) Inheritance of HbM (MIM 141800)... 

The iron of Hb must be maintained in the ferrous state ferric iron is reduced to the ferrous state by the action of an NADH-dependent methemoglobin reductase system involving cytochrome reductase and cytochrome b. ... 

Methemoglobinemia has long been associated with the absence of an NADH-linked diaphorase 362, 363). However, flavoproteins isolated from the red cell were never sufficiently active to account for the methemoglobin reductase activity calculated to be necessary. It has now been shown that a methemoglobin reductase system of high activity is composed of soluble forms of cytochrome bj reductase and cytochrome bs... 

A small but constant amount of methemoglobin is produced in the body. It is reduced by specific enzymes (methemoglobin reductases) and NADH, which is generated in glycolysis. Reductases isolated from human red cells also use NADPH but to a lesser extent. Inability to reduce metHb produces methemoglobinemiaand tissue anoxia. 

Methemoglobin reductase Red blood cell enzyme that uses nicotinamide adenine dinucleotide (NADH) to convert the iron of oxidized hemoglobin (methemoglobin) from the ferric (Fe +) to reduced ferrous state (Fe ) hemoglobin, which alone is capable of binding O,. 

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