Nicotinamide adenine dinucleotide phosphate, oxidized

NADP" nicotinamide adenine dinucleotide phosphate (oxidized form)... 

NADH reduced form of nicotinamide adenine dinucleotide NADP+ nicotinamide adenine dinucleotide phosphate (oxidized form) NADPH reduced form of nicotinamide dinucleotide phosphate Nj mole fraction of species) (dimensionless)... 

NADP+ nicotinamide adenine dinucleotide phosphate oxidized... 

NAD(P)+, nicotinamide adenine dinucleotide (phosphate), oxidized NAD(P)H, nicotinamide adenine dinucleotide (phosphate), reduced TRIPLE, electron-nuclear-nuclear triple resonance. 

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 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... 

Ethanol is oxidized by alcohol dehydrogenase (in the presence of nicotinamide adenine dinucleotide [NAD]) or the microsomal ethanol oxidizing system (MEOS) (in the presence of reduced nicotinamide adenine dinucleotide phosphate [NADPH]). Acetaldehyde, the first product in ethanol oxidation, is metabolized to acetic acid by aldehyde dehydrogenase in the presence of NAD. Acetic acid is broken down through the citric acid cycle to carbon dioxide (CO2) and water (H2O). Impairment of the metabolism of acetaldehyde to acetic acid is the major mechanism of action of disulfiram for the treatment of alcoholism. 

The most important product of the hexose monophosphate pathway is reduced nicotinamide-adenine dinucleotide phosphate (NADPH). Another important function of this pathway is to provide ribose for nucleic acid synthesis. In the red blood cell, NADPH is a major reducing agent and serves as a cofactor in the reduction of oxidized glutathione, thereby protecting the cell against oxidative attack. In the syndromes associated with dysfunction of the hexose monophosphate pathway and glutathione metabolism and synthesis, oxidative denaturation of hemoglobin is the major contributor to the hemolytic process. 

It is helpful to think of the photosynthesis reaction as the sum of an oxidation half reaction and a reduction half reaction as shown in Figure 1. In fact, nature does separate these half reactions, in that the reduction of C02 to carbohydrates occurs in the stroma of the chloroplast, the organelle in the leaf where the photosynthesis reaction occurs, - whereas, the light-driven oxidation half reaction takes place on the thylakoid membranes which make up the grana stacks within the chloroplast. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) carries the reducing power and most of the energy to the stroma to drive the fixation of C02 with the help of some additional energy provided... 

Figure 1. The separation of the half reaction in the chloroplast of the photosynthetic plant cell. The dark reaction (left) and the light-driven reactions (right) are shown. Key NADP oxidized form of nicotinamide adenine dinucleotide phosphate ATPf adenosine triphosphate and Pit inorganic phosphate.

VANONI, M.A., MATTHEWS, R.G., Kinetic isotope effects on the oxidation of reduced nicotinamide adenine dinucleotide phosphate by the flavoprotein methylenetetrahydrofolate reductase, Biochemistry, 1984, 23, 5272-5279. 

Endogenous NO is produced almost exclusively by L-arginine catabolism to L-citrul-line in a reaction catalyzed by a family of nitric oxide synthases (NOSs) [3]. In the first step, Arg is hydroxylated to an enzyme-bound intermediate "-hydroxy-1.-arginine (NHA), and 1 mol of NADPH (nicotinamide adenine dinucleotide phosphate, reduced form) and O2 are consumed. In the second step, N H A is oxidized to citrulline and NO, with consumption of 0.5 mol of NADPH and 1 mol of 02 (Scheme 1.1). Oxygen activation in both steps is carried out by the enzyme-bound heme, which derives electrons from NADPH. Mammalian NOS consists of an N-terminal oxy-... 

---