Canadian Medical Guide > Chemicals and Drugs > Enzymes and Coenzymes > Enzymes > Oxidoreductases > NADH, NADPH Oxidoreductases Terms and Definitions

NADH, NADPH Oxidoreductases

Medical Definition:	A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.
CAS Number:	EC 1.6.
Previously Indexed:	Oxidoreductases (1966-1972)

NADH, NADPH Oxidoreductases Categories.

	Cytochrome Reductases
	Dihydropteridine Reductase - An enzyme that catalyzes the reduction of 6,7-dihydropteridine to 5,6,7,8-tetrahydropteridine. EC 1.6.99.7.
	Ferredoxin-NADP Reductase - An enzyme that catalyzes the oxidation and reduction of ferredoxin or adrenodoxin in the presence of NADP. EC 1.18.1.2.
	Glutathione Reductase
	NAD(P)H-Flavin Oxidoreductase - An enzyme that utilizes NADH or NADPH to reduce FLAVINS. It is involved in a number of biological processes that require reduced flavin for their functions such as bacterial BIOLUMINESCENCE.
	NADH Tetrazolium Reductase - Catalyzes the reduction of tetrazolium compounds in the presence of NADH.
	NADP Transhydrogenase - An enzyme present in the mitochondrial membrane of animals and in microorganisms. In the presence of energy (ATP) it catalyzes reversibly the reduction of NAD by NADPH to yield NADP and NADH. This reaction permits the utilization of the reducing properties of NADPH by the respiratory chain and in the reverse direction it allows the reduction of NADP for biosynthetic purposes. EC 1.6.1.1.
	NADPH Dehydrogenase - A flavoprotein that reversibly oxidizes NADPH to NADP and a reduced acceptor. EC 1.6.99.1.
	NADPH Oxidase - A plasma membrane-associated enzyme complex that catalyzes the univalent reduction of oxygen using NADPH as an electron donor. The superoxide anion formed acts as an oxidant in the phagocyte microbicidal system, proceeding through a series of electron transfer reactions that form the respiratory burst. Various genetic defects in the system result in chronic granulomatous disease (GRANULOMATOUS DISEASE, CHRONIC). (Dorland, 28th ed) EC 1.6.-.
	Nitrate Reductases
	Nitrite Reductases - A group of enzymes that oxidize diverse nitrogenous substances to yield nitrite. (Enzyme Nomenclature, 1992) EC 1.
	Quinone Reductases - NAD(P)H:(quinone acceptor) oxidoreductases. A family that includes three enzymes which are distinguished by their sensitivity to various inhibitors. EC 1.6.99.2 (NAD(P)H DEHYDROGENASE (QUINONE)); is a flavoprotein which reduces various quinones in the presence of NADH or NADPH and is inhibited by dicoumarol. EC 1.6.99.5 (NADH dehydrogenase (quinone)) requires NADH, is inhibited by AMP and 2,4-dinitrophenol but not by dicoumarol or folic acid derivatives. EC 1.6.99.6 (NADPH dehydrogenase (quinone)) requires NADPH and is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol.
	Thioredoxin Reductase (NADPH) - NADPH:oxidized thioredoxin oxidoreductase.

NADH, NADPH Oxidoreductases Medical Definitions and Terms

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