NADP nicotinamide adenine dinucleotide phosphate

Indicators There are certain compounds that are suitable as indicators for sensitive and specific clinical analysis. Nicotinamide adenine dinucleotide (NAD) occurs in oxidized (NAD" ) and reduced (NADH) forms. Nicotinamide adenine dinucleotide phosphate (NADP) also has two states, NADP" and NADPH. NADH has a very high uv—vis absorption at 339 nm, extinction coefficient = 6300 (M cm) , but NAD" does not. Similarly, NADPH absorbs light very strongly whereas NADP" does not. 

In oiological systems, the most frequent mechanism of oxidation is the remov of hydrogen, and conversely, the addition of hydrogen is the common method of reduc tion. Nicotinamide-adenine dinucleotide (NAD) and nicotinamide-adenine dinucleotide phosphate (NADP) are two coenzymes that assist in oxidation and reduction. These cofactors can shuttle between biochemical reac tions so that one drives another, or their oxidation can be coupled to the formation of ATP. However, stepwise release or consumption of energy requires driving forces and losses at each step such that overall efficiency suffers. 

Nicotinamide adenine dinucleotide phosphate (NADP, TPN) [53-59-8] M 743.4, pK] 1.1 (PO4H2), pK 4.0 (adenine NH ), pKa 6.1 (P04 ). Purified by anion-exchange chromatography in much the same way as for NAD [Dalziel and Dickinson Biochem J 95 311 7965 Biochemical Preparations 11 87 7966]. Finally it is purified by dissolving in H2O and precipitating with 4 volumes of Me2CO and dried in... 

Nicotinamide is an essential part of two important coenzymes nicotinamide adenine dinucleotide (NAD ) and nicotinamide adenine dinucleotide phosphate (NADP ) (Figure 18.19). The reduced forms of these coenzymes are NADH and NADPH. The nieotinamide eoenzymes (also known as pyridine nucleotides) are electron carriers. They play vital roles in a variety of enzyme-catalyzed oxidation-reduction reactions. (NAD is an electron acceptor in oxidative (catabolic) pathways and NADPH is an electron donor in reductive (biosynthetic) pathways.) These reactions involve direct transfer of hydride anion either to NAD(P) or from NAD(P)H. The enzymes that facilitate such... 

These dehydrogenases use nicotinamide adenine dinucleotide (NAD ) or nicotinamide adenine dinucleotide phosphate (NADP )—or both—and are formed in the body from the vitamin niacin (Chapter 45). The coenzymes are reduced by the specific substrate of the dehydrogenase and reoxidized by a suitable electron acceptor (Figure 11-4). They may freely and reversibly dissociate from their respective apoenzymes. 

Nicotinamide Adenine Dinucleotide phosphate (NADP+) Glutamate dehydrogenase, Alcohol dehydrogenase, Aryl-aldehyde dehydrogenase... 

The second type of biological electron transfer involves a variety of small molecules, both organic and inorganic. Examples of these are (a) nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) as two electron carriers and (b) quinones and flavin mononucleotide (FMN), which may transfer one or two electrons. The structure of NAD and its reduced counterpart NADH are shown in Figure 1.12. 

Nicotinic acid derivatives occur in biologic materials as the free acid, as nicotinamide, and in two coenzymatic forms nicotinamide adenine dinucleotide (NAD), and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes act in series with flavoprotein enzymes and, like them, are hydrogen acceptors or, when reduced, donors. Several plants and bacteria use a metabolic pathway for the formation of nicotinic acid that is different from the tryptophan pathway used by animals and man (B39). 

X = PO32" Nicotinamide adenine dinucleotide phosphate (NADP+)... 

Although the structures for molecules having niacin activity are simple, the forms in which they act in human biochemistry are not so simple. Nicotinic acid and nicotinamide are precursors for three complex coenzymes in multiple oxida-tion/reduction (redox) reactions nicotinamide mononucleotide, NMN nicotinamide adenine dinucleotide, NAD+ and nicotinamide adenine dinucleotide phosphate, NADP. I shall use NAD+ as representative of the class. NADH is the corresponding reduced form. ... 

Nicotinate and nicotinamide, together referred to as niacin, are required for biosynthesis of the coenzymes nicotinamide adenine dinucleotide (NAD"") and nicotinamide adenine dinucleotide phosphate (NADP" ). These both serve in energy and nutrient metabolism as carriers of hydride ions (see pp. 32, 104). The animal organism is able to convert tryptophan into nicotinate, but only with a poor yield. Vitamin deficiency therefore only occurs when nicotinate, nicotinamide, and tryptophan are all simultaneously are lacking in the diet. It manifests in the form of skin damage (pellagra), digestive disturbances, and depression. 

Niacin is also known as vitamin PP or vitamin Bj. The term niacin describes two related compounds, nicotinic acid and nicotinamide (Figure 19.18), both with biological activity. Niacin is formed from the metabolism of tryptophan, and therefore it is not strictly a vitamin. It is a precursor of two cofactors nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are essential for the functioning of a wide range of enzymes involved in redox reactions. 

Niacin is a generic term which refers to two related chemical compounds, nicotinic acid (6.22) and its amide, nicotinamide (6.23) both are derivatives of pyridine. Nicotinic acid is synthesized chemically and can be easily converted to the amide in which form it is found in the body. Niacin is obtained from food or can be synthesized from tryptophan (60 mg of dietary tryptophan has the same metabolic effect as 1 mg niacin). Niacin forms part of two important co-enzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are co-factors for many enzymes that participate in various metabolic pathways and function in electron transport. 

Nicotinamide adenine dinucleotide (NAD+ in its oxidized form) and its close analog nicotinamide adenine dinucleotide phosphate (NADP+) are composed of two nucleotides joined through their phosphate groups by a phosphoanhydride bond (Fig. 13-15a). Because the nicotinamide ring resembles pyridine, these compounds are sometimes called pyridine nucleotides. The vitamin niacin is the source of the nicotinamide moiety in nicotinamide nucleotides. 

Two vitamins, nicotinamide and pyridoxine (vitamin B6), are pyridine derivatives. Nicotinamide participates in two coenzymes, coenzyme I (65 R = H) which is known variously as nicotinamide adenine dinucleotide (NAD) or diphosphopyridine nucleotide (DPN), and coenzyme II (65 R = P03H2) also called triphosphopyridine nucleotide (TPN) or nicotinamide adenine dinucleotide phosphate (NADP). These are involved in many oxidation-reduction processes, the quaternized pyridine system acting as a hydrogen acceptor and hydrogen donor. Deficiency of nicotinamide causes pellagra, a disease associated with an inadequately supplemented maize diet. Nicotinic acid (niacin) and its amide are... 

Two derivatives of nicotinamide (pyridine-3-carboxylic amide), one of the B2 vitamins, nicotinamide adenine dinucleotide (NAD ) and nicotinamide adenine dinucleotide phosphate (NADP ), serve as redox coenzymes. Of the three heterocyclic ring systems found in these coenzymes, i.e. those of purine, ribose and pyridine, it is the pyridine portion that is reactive in redox reactions. Biologically, two oxidation states are important the oxidized form, NAD(P)+, and the 1,4-dihydro isomer of the two-electron reduced form, NAD(P)H (Scheme 1). Nicotinamide coenzymes interconvert between these two oxidation states in... 

Niacin, a water-soluble vitamin vital for oxidation by living cells, functions in the body as a component of two important coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). NAD and NADP are involved in the release of energy from carbohydrate, fat, and protein, and in the synthesis of protein, fat, and pentoses for nucleic acid formation. Milk is a poor source of preformed niacin, containing about 0.08 mg per 100 g. However, milk s niacin value is considerably greater than indicated by its niacin content (Horwitt et al. 1981). Not only is the niacin in milk fully available, but the amino acid tryptophan in milk can be used by the body for the synthesis of niacin. For every 60 mg of tryptophan consumed, the body synthesizes 1 mg of niacin. Therefore, the niacin equivalents in 100 g milk equal 0.856 mg including that from pre-... 

FMN was first identified as the coenzyme of an enzyme system that catalyzes the oxidation of the reduced nicotinamide coenzyme, NADPH (reduced NADP), to NADP (nicotinamide adenine dinucleotide phosphate). NADP is an essential coenzyme for glucose-6-phosphate dehydrogenase which catalyzes the oxidation of glucose-6-phosphate to 6-phosphogluconrc acid. This reaction initiates the metabolism of glucose by a pathway other than the TCA cycle (citric acid cycle). The alternative route is known as the phosphoglneonate oxidative pathway, or the hexose monophosphate shunt. The first step is ... 

One photoprocess reduces nicotinamide adenine dinucleotide phosphate (NADP ) to NADPH. These dinucleotides, shown below, differ from NAD and NADH (Section 15-6C) in having a phosphate group at C2 of one of the ribose units. The oxidized form, NADP , behaves like NAD and receives the equivalent of H e at C4 of the nicotinamide ring to form NADPH ... 

NAD) and nicotinamide adenine dinucleotide phosphate (NADP), are the universal carriers of hydrogen and electrons, or metabolic reducing power. Many redox processes may be linked together in electron transport chains. 

The niacin vitamers in foods include nicotinic acid and nicotinamide (Fig. 4), which occur in limited quantities in the free form, and their coenzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) (93,96). The nicotinic acid analog of NAD as well as nicotinamide and nicotinic acid mononucleotides also occur in nature. In addition, niacin occurs as nicotinyl esters bound to polysaccharides, peptides, and glycopep-tides, which are known as niacytin and niacynogens, respectively. In general, the niacin vitamers in cereal grains and other seeds are principally the nicotinic acid forms, whereas those in meat and fish are primarily the nicotinamide forms (94,95). 

Phosphate group in Nicotinamide Adenine Dinucleotide Phosphate (NADP)... 

A reversible covalent modification that plants use extensively is the reduction of cystine disulfide bridges to sulf-hydryls. Many of the enzymes of photosynthetic carbohydrate synthesis are activated in this way (table 9.3). Some of the enzymes of carbohydrate breakdown are inactivated by the same mechanism. The reductant is a small protein called thioredoxin, which undergoes a complementary oxidation of cysteine residues to cystine (fig. 9.5). Thioredoxin itself is reduced by electron-transfer reactions driven by sunlight, which serves as a signal to switch carbohydrate metabolism from carbohydrate breakdown to synthesis. In one of the regulated enzymes, phosphoribulokinase, one of the freed cysteines probably forms part of the catalytic active site. In nicotinamide-adenine dinucleotide phosphate (NADP)-malate dehydrogenase and fructose-1,6-bis-... 

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