NADH

nicotinamide adenine dinucleotide (NAD) carrying two electrons and bonded with a hydrogen (H) ion; the reduced form of NAD.

— Wiktionary

nicotinamide adenine dinucleotide phosphate, NADP

a coenzyme similar to NAD and present in most living cells but serves as a reductant in different metabolic processes

— Princeton's WordNet

nicotinamide adenine dinucleotide phosphate, NADP

a coenzyme similar to NAD and present in most living cells but serves as a reductant in different metabolic processes

— Princeton's WordNet

depth-first search

an algorithm for traversing a tree or graph where one starts at the root nad explores as far as possible along each branch before backtracking

— Wiktionary

homolactic fermentation

Any form of fermentation that produces a single acid, but especially the anaerobic conversion of pyruvic acid into lactic acid with concomitant oxidation of NADH to NAD

— Wiktionary

Galactose Dehydrogenases

D-Galactose:NAD(P)+ 1-oxidoreductases. Catalyzes the oxidation of D-galactose in the presence of NAD+ or NADP+ to D-galactono-gamma-lactone and NADH or NADPH. Includes EC 1.1.1.48 and EC 1.1.1.120.

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Saccharopine Dehydrogenases

Amine oxidoreductases that use either NAD+ (EC 1.5.1.7) or NADP+ (EC 1.5.1.8) as an acceptor to form L-LYSINE or NAD+ (EC 1.5.1.9) or NADP+ (EC 1.5.1.10) as an acceptor to form L-GLUTAMATE. Deficiency of this enzyme causes HYPERLYSINEMIAS.

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O-Acetyl-ADP-Ribose

An acetyl ester of ADENOSINE DIPHOSPHATE RIBOSE formed during NAD-dependent deacetylation of proteins by SIRTUINS. The acetate group resides on the ribose ring where nicotinamide was cleaved from NAD during the reaction. Several isomers of O-acetyl-ADP-ribose have been isolated from the reaction.

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Sirtuins

A homologous family of regulatory enzymes that are structurally related to the protein silent mating type information regulator 2 (Sir2) found in Saccharomyces cerevisiae. Sirtuins contain a central catalytic core region which binds NAD. Several of the sirtuins utilize NAD to deacetylate proteins such as HISTONES and are categorized as GROUP III HISTONE DEACETYLASES. Several other sirtuin members utilize NAD to transfer ADP-RIBOSE to proteins and are categorized as MONO ADP-RIBOSE TRANSFERASES, while a third group of sirtuins appears to have both deacetylase and ADP ribose transferase activities.

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Nicotinamide-Nucleotide Adenylyltransferase

An enzyme that catalyzes reversibly the transfer of the adenylyl moiety of ATP to the phosphoryl group of NMN to form NAD+ and pyrophosphate. The enzyme is found predominantly in the nuclei and catalyzes the final reaction in the major pathway for the biosynthesis of NAD in mammals. EC 2.7.7.1.

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Betaine-Aldehyde Dehydrogenase

An NAD+ dependent enzyme that catalyzes the oxidation of betain aldehyde to BETAINE.

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Glycolaldehyde Dehydrogenase

An enzyme that catalyzes the oxidation of glycolaldehyde to glycolate, using NAD and NADP as COENZYMES.

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Cyclic ADP-Ribose

A pyridine nucleotide that mobilizes CALCIUM. It is synthesized from nicotinamide adenine dinucleotide (NAD) by ADP RIBOSE CYCLASE.

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Aminomuconate-Semialdehyde Dehydrogenase

An NAD+ dependent enzyme that catalyzes the oxidation of 2-aminomuconate 6-semialdehyde to 2-aminomuconate.

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Glycerol-3-Phosphate Dehydrogenase (NAD+)

An NAD-dependent enzyme that catalyzes the oxidation of sn-glycerol 3-phosphate to glycerone phosphate.

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Malate Dehydrogenase

An enzyme that catalyzes the conversion of (S)-malate and NAD+ to oxaloacetate and NADH. EC 1.1.1.37.

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Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent

Specific hydroxymethylglutaryl CoA reductases that utilize the cofactor NAD. In liver enzymes of this class are involved in cholesterol biosynthesis.

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Acetoin Dehydrogenase

An enzyme that catalyzes the conversion of acetoin to diacetyl in the presence of NAD. EC 1.1.1.5.

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Poly Adenosine Diphosphate Ribose

A polynucleotide formed from the ADP-RIBOSE moiety of nicotinamide-adenine dinucleotide (NAD) by POLY(ADP-RIBOSE) POLYMERASES.

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Uridine Diphosphate Glucose Dehydrogenase

An enzyme that catalyzes the oxidation of UDPglucose to UDPglucuronate in the presence of NAD+. EC 1.1.1.22.

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2-Oxoisovalerate Dehydrogenase (Acylating)

An NAD+ dependent enzyme that catalyzes the oxidation 3-methyl-2-oxobutanoate to 2-methylpropanoyl-CoA. It plays a role in the degradation of VALINE; LEUCINE; and ISOLEUCINE.

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Methylenetetrahydrofolate Dehydrogenase (NAD+)

A NAD-dependent oxidoreductase that catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5,10-methenyl-tetrahdyrofolate. It has been found in a variety of microorganisms.

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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.

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11-beta-Hydroxysteroid Dehydrogenases

Hydroxysteroid dehydrogenases that catalyzes the reversible conversion of CORTISOL to the inactive metabolite CORTISONE. Enzymes in this class can utilize either NAD or NADP as cofactors.

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Glucose 1-Dehydrogenase

A glucose dehydrogenase that catalyzes the oxidation of beta-D-glucose to form D-glucono-1,5-lactone, using NAD as well as NADP as a coenzyme.

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Dihydrolipoamide Dehydrogenase

A flavoprotein containing oxidoreductase that catalyzes the reduction of lipoamide by NADH to yield dihydrolipoamide and NAD+. The enzyme is a component of several MULTIENZYME COMPLEXES.

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Sirtuin 1

A sirtuin family member found primarily in the CELL NUCLEUS. It is an NAD-dependent deacetylase with specificity towards HISTONES and a variety of proteins involved in gene regulation.

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Myo-Inositol-1-Phosphate Synthase

An enzyme that catalyzes the formation of myo-inositol-1-phosphate from glucose-6-phosphate in the presence of NAD. EC 5.5.1.4.

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IMP Dehydrogenase

An enzyme that catalyzes the dehydrogenation of inosine 5'-phosphate to xanthosine 5'-phosphate in the presence of NAD. EC 1.1.1.205.

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Group III Histone Deacetylases

A subclass of histone deacetylases that are NAD-dependent. Several members of the SIRTUINS family are included in this subclass.

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UDPglucose 4-Epimerase

A necessary enzyme in the metabolism of galactose. It reversibly catalyzes the conversion of UDPglucose to UDPgalactose. NAD+ is an essential component for enzymatic activity. EC 5.1.3.2.

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Fructuronate Reductase

An enzyme that catalyzes the reversible oxidation of mannonate to fructuronate in the presence of NAD. Also reduces D-tagaturonate to D-altronate. EC 1.1.1.57.

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3-Isopropylmalate Dehydrogenase

An NAD+ dependent enzyme that catalyzes the oxidation of 3-carboxy-2-hydroxy-4-methylpentanoate to 3-carboxy-4-methyl-2-oxopentanoate. It is involved in the biosynthesis of VALINE; LEUCINE; and ISOLEUCINE.

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Sirtuin 3

A sirtuin family member found primarily in MITOCHONDRIA. It is a multifunctional enzyme that contains a NAD-dependent deacetylase activity that is specific for HISTONES and a mono-ADP-ribosyltransferase activity.

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Dihydrouracil Dehydrogenase (NAD+)

An enzyme that catalyzes the oxidation of 5,6-dihydrouracil to URACIL using NAD as a cofactor. This enzyme also plays a role in the catabolism of the antimetabolite 5-FLUOROURACIL.

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Aldehyde Dehydrogenase

An enzyme that oxidizes an aldehyde in the presence of NAD+ and water to an acid and NADH. This enzyme was formerly classified as EC 1.1.1.70.

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Sirtuin 2

A sirtuin family member found primarily in the CYTOPLASM. It is a multifunctional enzyme that contains a NAD-dependent deacetylase activity that is specific for HISTONES and a mono-ADP-ribosyltransferase activity.

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Glutamate Dehydrogenase

An enzyme that catalyzes the conversion of L-glutamate and water to 2-oxoglutarate and NH3 in the presence of NAD+. (From Enzyme Nomenclature, 1992) EC 1.4.1.2.

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L-Lactate Dehydrogenase

A tetrameric enzyme that, along with the coenzyme NAD+, catalyzes the interconversion of LACTATE and PYRUVATE. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist.

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Hydroxymethylglutaryl-CoA Reductases, NAD-Dependent

Specific hydroxymethylglutaryl CoA reductases that utilize the cofactor NAD. This class of enzymes performs a catabolic role in microorganisms such as Pseudomonas mevalonii where it oxidatively acetylates MEVALONIC ACID to form 3-HYDROXY-3-METHYLGLUTARYL-COENZYME A and NADH.

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zeta-Crystallins

A group of crystallins that have been found in the lens (LENS, CRYSTALLINE) of certain species of VERTEBRATES including GUINEA PIGS; CAMELS; and LLAMAS. They are inactivated forms of NAD(P)H DEHYDROGENASE (QUINONE).

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D-Xylulose Reductase

An enzyme that plays a role in the PENTOSES and GLUCURONATES interconversion pathway by catalyzing the oxidation of XYLITOL to D-xylulose. This enzyme has been found to be specific for NAD+.

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Xanthine Dehydrogenase

An enzyme that catalyzes the oxidation of XANTHINE in the presence of NAD+ to form URIC ACID and NADH. It acts also on a variety of other purines and aldehydes.

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Glutamate Synthase (NADH)

A FLAVOPROTEIN enzyme for AMMONIA assimilation in BACTERIA, microorganisms and PLANTS. It catalyzes the oxidation of 2 molecules of L-GLUTAMATE to generate L-GLUTAMINE and 2-oxoglutarate in the presence of NAD+.

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Dihydrodipicolinate Reductase

An enzyme that catalyzes the oxidation of 2,3,4,5-tetrahydrodipicolinate to 2,3-dihydrodipicolinate using NAD(P)+ as a cofactor. It is found in BACTERIA and higher plants involved in the biosynthesis of DIAMINOPIMELIC ACID and LYSINE.

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Poly(ADP-ribose) Polymerases

Enzymes that catalyze the transfer of multiple ADP-RIBOSE groups from nicotinamide-adenine dinucleotide (NAD) onto protein targets, thus building up a linear or branched homopolymer of repeating ADP-ribose units i.e., POLY ADENOSINE DIPHOSPHATE RIBOSE.

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1-Pyrroline-5-Carboxylate Dehydrogenase

An enzyme that catalyzes the oxidation of 1-pyrroline-5-carboxylate to L-GLUTAMATE in the presence of NAD. Defects in the enzyme are the cause of hyperprolinemia II.

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Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)

An NAD-dependent enzyme that catalyzes the oxidation of acyl-[acyl-carrier protein] to trans-2,3-dehydroacyl-[acyl-carrier protein]. It has a preference for acyl groups with a carbon chain length between 4 to 16.

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Antigens, CD38

A bifunctional enzyme that catalyzes the synthesis and HYDROLYSIS of CYCLIC ADP-RIBOSE (cADPR) from NAD+ to ADP-RIBOSE. It is a cell surface molecule which is predominantly expressed on LYMPHOID CELLS and MYELOID CELLS.

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Progesterone Reductase

An enzyme that catalyzes the reduction of a 3 beta-hydroxy-delta(5)-steroid to 3-oxo-delta(4)-steroid in the presence of NAD. It converts pregnenolone to progesterone and dehydroepiandrosterone to androstenedione. EC 1.1.1.145.

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Niacin

A water-soluble vitamin of the B complex occurring in various animal and plant tissues. It is required by the body for the formation of coenzymes NAD and NADP. It has PELLAGRA-curative, vasodilating, and antilipemic properties.

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Leucine Dehydrogenase

An octameric enzyme belonging to the superfamily of amino acid dehydrogenases. Leucine dehydrogenase catalyzes the reversible oxidative deamination of L-LEUCINE, to 4-methyl-2-oxopentanoate (2-ketoisocaproate) and AMMONIA, with the corresponding reduction of the cofactor NAD+.

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Methylmalonate-Semialdehyde Dehydrogenase (Acylating)

An enzyme that plays a role in the VALINE; LEUCINE; and ISOLEUCINE catabolic pathways by catalyzing the oxidation of 2-methyl-3-oxopropanate to propanoyl-CoA using NAD+ as a coenzyme. Methylmalonate semialdehyde dehydrogenase deficiency is characterized by elevated BETA-ALANINE and 3-hydropropionic acid.

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11-beta-Hydroxysteroid Dehydrogenase Type 1

A low-affinity 11 beta-hydroxysteroid dehydrogenase found in a variety of tissues, most notably in LIVER; LUNG; ADIPOSE TISSUE; vascular tissue; OVARY; and the CENTRAL NERVOUS SYSTEM. The enzyme acts reversibly and can use either NAD or NADP as cofactors.

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Alcohol Oxidoreductases

A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).

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Prephenate Dehydrogenase

An enzyme that catalyzes the conversion of prephenate to p-hydroxyphenylpyruvate in the presence of NAD. In the enteric bacteria, this enzyme also possesses chorismate mutase activity, thereby catalyzing the first two steps in the biosynthesis of tyrosine. EC 1.3.1.12.

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Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating)

An NAD-dependent glyceraldehyde-3-phosphate dehydrogenase found in the cytosol of eucaryotes. It catalyses the dehydrogenation and phosphorylation of GLYCERALDEHYDE 3-PHOSPHATE to 3-phospho-D-glyceroyl phosphate, which is an important step in the GLYCOLYSIS pathway.

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Nitrite Reductase (NAD(P)H)

An enzyme found primarily in BACTERIA and FUNGI that catalyzes the oxidation of ammonium hydroxide to nitrite. It is an iron-sulfur HEME; FLAVOPROTEIN containing siroheme and can utilize both NAD and NADP as cofactors. This enzyme was formerly classified as EC 1.6.6.4.

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Adenosine Diphosphate Ribose

An ester formed between the aldehydic carbon of RIBOSE and the terminal phosphate of ADENOSINE DIPHOSPHATE. It is produced by the hydrolysis of nicotinamide-adenine dinucleotide (NAD) by a variety of enzymes, some of which transfer an ADP-ribosyl group to target proteins.

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Retinal Dehydrogenase

A metalloflavoprotein enzyme involved the metabolism of VITAMIN A, this enzyme catalyzes the oxidation of RETINAL to RETINOIC ACID, using both NAD+ and FAD coenzymes. It also acts on both the 11-trans- and 13-cis-forms of RETINAL.

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DNA Ligases

Poly(deoxyribonucleotide):poly(deoxyribonucleotide)ligases. Enzymes that catalyze the joining of preformed deoxyribonucleotides in phosphodiester linkage during genetic processes during repair of a single-stranded break in duplex DNA. The class includes both EC 6.5.1.1 (ATP) and EC 6.5.1.2 (NAD).

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Nicotinamide Phosphoribosyltransferase

An enzyme that catalyzes the formation of nicotinamide mononucleotide (NMN) from nicotinamide and 5-phosphoribosyl-1-pyrophosphate, the rate-limiting step in the biosynthesis of the NAD coenzyme. It is also known as a growth factor for early B-LYMPHOCYTES, or an ADIPOKINE with insulin-mimetic effects (visfatin).

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15-Oxoprostaglandin 13-Reductase

(5Z)-(15S)-11 alpha-Hydroxy-9,15-dioxoprostanoate:NAD(P)+ delta(13)-oxidoreductase. An enzyme active in prostaglandin E and F catabolism. It catalyzes the reduction of the double bond at the 13-14 position of the 15-ketoprostaglandins and uses NADPH as cofactor. EC 1.3.1.48.

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Alcohol Dehydrogenase

A zinc-containing enzyme which oxidizes primary and secondary alcohols or hemiacetals in the presence of NAD. In alcoholic fermentation, it catalyzes the final step of reducing an aldehyde to an alcohol in the presence of NADH and hydrogen.

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NAD

A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)

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Aryl Hydrocarbon Hydroxylases

A large group of cytochrome P-450 (heme-thiolate) monooxygenases that complex with NAD(P)H-FLAVIN OXIDOREDUCTASE in numerous mixed-function oxidations of aromatic compounds. They catalyze hydroxylation of a broad spectrum of substrates and are important in the metabolism of steroids, drugs, and toxins such as PHENOBARBITAL, carcinogens, and insecticides.

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Nitrate Reductase (NADPH)

An enzyme that catalyzes the oxidation of nitrite to nitrate in the presence of NADP+. It is a FLAVOPROTEIN that contains IRON and MOLYBDENUM. This enzyme was formerly classified as EC 1.6.6.3 and should not be confused with the enzyme NITRATE REDUCTASE (NAD(P)H).

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3-Hydroxyacyl CoA Dehydrogenases

Enzymes that reversibly catalyze the oxidation of a 3-hydroxyacyl CoA to 3-ketoacyl CoA in the presence of NAD. They are key enzymes in the oxidation of fatty acids and in mitochondrial fatty acid synthesis. EC 1.1.1.35.

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Niacinamide

An important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and PELLAGRA. Most animals cannot manufacture this compound in amounts sufficient to prevent nutritional deficiency and it therefore must be supplemented through dietary intake.

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Succinate-Semialdehyde Dehydrogenase

An enzyme that plays a role in the GLUTAMATE and butanoate metabolism pathways by catalyzing the oxidation of succinate semialdehyde to SUCCINATE using NAD+ as a coenzyme. Deficiency of this enzyme, causes 4-hydroxybutyricaciduria, a rare inborn error in the metabolism of the neurotransmitter 4-aminobutyric acid (GABA).

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NAD+ Nucleosidase

An enzyme that catalyzes the hydrolysis of nicotinamide adenine dinucleotide (NAD) to NICOTINAMIDE and ADENOSINE DIPHOSPHATE RIBOSE. Some are extracellular (ectoenzymes).The enzyme from some sources also catalyses the hydrolysis of nicotinamide adenine dinucleotide phosphate (NADP).

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Estradiol Dehydrogenases

Enzymes that catalyze the oxidation of estradiol at the 17-hydroxyl group in the presence of NAD+ or NADP+ to yield estrone and NADH or NADPH. The 17-hydroxyl group can be in the alpha- or beta-configuration. EC 1.1.1.62

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3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)

A 3-hydroxysteroid dehydrogenase which catalyzes the reversible reduction of the active androgen, DIHYDROTESTOSTERONE to 5 ALPHA-ANDROSTANE-3 ALPHA,17 BETA-DIOL. It also has activity towards other 3-alpha-hydroxysteroids and on 9-, 11- and 15- hydroxyprostaglandins. The enzyme is B-specific in reference to the orientation of reduced NAD or NADPH.

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Nitrate Reductase (NADH)

An NAD-dependent enzyme that catalyzes the oxidation of nitrite to nitrate. It is a FLAVOPROTEIN that contains IRON and MOLYBDENUM and is involved in the first step of nitrate assimilation in PLANTS; FUNGI; and BACTERIA. It was formerly classified as EC 1.6.6.1.

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NADH Dehydrogenase

A flavoprotein and iron sulfur-containing oxidoreductase that catalyzes the oxidation of NADH to NAD. In eukaryotes the enzyme can be found as a component of mitochondrial electron transport complex I. Under experimental conditions the enzyme can use CYTOCHROME C GROUP as the reducing cofactor. The enzyme was formerly listed as EC 1.6.2.1.

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Glycine Dehydrogenase

An oxidoreductase that catalyzes the oxidative DEAMINATION of GLYCINE to glyoxylate and AMMONIA in the presence of NAD. In BACTERIA lacking transaminating pathways the enzyme can act in the reverse direction to synthesize glycine from glyoxylate and ammonia and NADH.

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L-Iditol 2-Dehydrogenase

An alcohol oxidoreductase which catalyzes the oxidation of L-iditol to L-sorbose in the presence of NAD. It also acts on D-glucitol to form D-fructose. It also acts on other closely related sugar alcohols to form the corresponding sugar. EC 1.1.1.14

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Alanine Dehydrogenase

An NAD-dependent enzyme that catalyzes the reversible DEAMINATION of L-ALANINE to PYRUVATE and AMMONIA. The enzyme is needed for growth when ALANINE is the sole CARBON or NITROGEN source. It may also play a role in CELL WALL synthesis because L-ALANINE is an important constituent of the PEPTIDOGLYCAN layer.

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11-beta-Hydroxysteroid Dehydrogenase Type 2

An high-affinity, NAD-dependent 11-beta-hydroxysteroid dehydrogenase that acts unidirectionally to catalyze the dehydrogenation of CORTISOL to CORTISONE. It is found predominantly in mineralocorticoid target tissues such as the KIDNEY; COLON; SWEAT GLANDS; and the PLACENTA. Absence of the enzyme leads to a fatal form of childhood hypertension termed, APPARENT MINERALOCORTICOID EXCESS SYNDROME.

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Histone Deacetylases

Deacetylases that remove N-acetyl groups from amino side chains of the amino acids of HISTONES. The enzyme family can be divided into at least three structurally-defined subclasses. Class I and class II deacetylases utilize a zinc-dependent mechanism. The sirtuin histone deacetylases belong to class III and are NAD-dependent enzymes.

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Glyceraldehyde-3-Phosphate Dehydrogenases

Enzymes that catalyze the dehydrogenation of GLYCERALDEHYDE 3-PHOSPHATE. Several types of glyceraldehyde-3-phosphate-dehydrogenase exist including phosphorylating and non-phosphorylating varieties and ones that transfer hydrogen to NADP and ones that transfer hydrogen to NAD.

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Nitrate Reductase (NAD(P)H)

An iron-sulfur and MOLYBDENUM containing FLAVOPROTEIN that catalyzes the oxidation of nitrite to nitrate. This enzyme can use either NAD or NADP as cofactors. It is a key enzyme that is involved in the first step of nitrate assimilation in PLANTS; FUNGI; and BACTERIA. This enzyme was formerly classified as EC 1.6.6.2.

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ADP-ribosyl Cyclase

A membrane-bound or cytosolic enzyme that catalyzes the synthesis of CYCLIC ADP-RIBOSE (cADPR) from nicotinamide adenine dinucleotide (NAD). This enzyme generally catalyzes the hydrolysis of cADPR to ADP-RIBOSE, as well, and sometimes the synthesis of cyclic ADP-ribose 2' phosphate (2'-P-cADPR) from NADP.

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Pyrroline Carboxylate Reductases

A group of enzymes that catalyze the reduction of 1-pyrroline carboxylate to proline in the presence of NAD(P)H. Includes both the 2-oxidoreductase (EC 1.5.1.1) and the 5-oxidoreductase (EC 1.5.1.2). The former also reduces 1-piperidine-2-carboxylate to pipecolate and the latter also reduces 1-pyrroline-3-hydroxy-5-carboxylate to hydroxyproline.

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NADH, NADPH Oxidoreductases

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.

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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.

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ADP Ribose Transferases

Enzymes that transfer the ADP-RIBOSE group of NAD or NADP to proteins or other small molecules. Transfer of ADP-ribose to water (i.e., hydrolysis) is catalyzed by the NADASES. The mono(ADP-ribose)transferases transfer a single ADP-ribose. POLY(ADP-RIBOSE) POLYMERASES transfer multiple units of ADP-ribose to protein targets, building POLY ADENOSINE DIPHOSPHATE RIBOSE in linear or branched chains.

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Silent Information Regulator Proteins, Saccharomyces cerevisiae

A set of nuclear proteins in SACCHAROMYCES CEREVISIAE that are required for the transcriptional repression of the silent mating type loci. They mediate the formation of silenced CHROMATIN and repress both transcription and recombination at other loci as well. They are comprised of 4 non-homologous, interacting proteins, Sir1p, Sir2p, Sir3p, and Sir4p. Sir2p, an NAD-dependent HISTONE DEACETYLASE, is the founding member of the family of SIRTUINS.

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Isocitrate Dehydrogenase

An enzyme of the oxidoreductase class that catalyzes the conversion of isocitrate and NAD+ to yield 2-ketoglutarate, carbon dioxide, and NADH. It occurs in cell mitochondria. The enzyme requires Mg2+, Mn2+; it is activated by ADP, citrate, and Ca2+, and inhibited by NADH, NADPH, and ATP. The reaction is the key rate-limiting step of the citric acid (tricarboxylic) cycle. (From Dorland, 27th ed) (The NADP+ enzyme is EC 1.1.1.42.) EC 1.1.1.41.

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Formate Dehydrogenases

Flavoproteins that catalyze reversibly the reduction of carbon dioxide to formate. Many compounds can act as acceptors, but the only physiologically active acceptor is NAD. The enzymes are active in the fermentation of sugars and other compounds to carbon dioxide and are the key enzymes in obtaining energy when bacteria are grown on formate as the main carbon source. They have been purified from bovine blood. EC 1.2.1.2.

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