Nicotinamide diphosphate

All NiFe hydrogenases comprise at least two subunits of molecular weights ca 60 and 30kDa respectively. The metal content comprises a NiFe centre and at least two Fe4S4 clusters. The NAD (nicotinamide diphosphate) reducing... 

Nicotinamide is incorporated into NAD and nicotinamide is the primary ckculating form of the vitamin. NAD has two degradative routes by pyrophosphatase to form AMP and nicotinamide mononucleotide and by hydrolysis to yield nicotinamide adenosine diphosphate ribose. 

Coenzymes such as adenosine diphosphate (ADP), adenosine SGtriphosphate (ATP), nicotinamide adenine dinucleotide (NAD), and nicotinamide adenine dinucleotide, reduced (NADH), are involved in some reactions (4). 

Abbreviations NADPH, b-nicotinamide adenine dinucleotide phosphate reduced from 5 -phosphosulfate UDPGA, uridine diphosphate-glucuronic acid. 

Figure 17-5. Oxidative decarboxylation of pyruvate by the pyruvate dehydrogenase complex. Lipoic acid is joined by an amide link to a lysine residue of the transacetylase component of the enzyme complex. It forms a long flexible arm, allowing the lipoic acid prosthetic group to rotate sequentially between the active sites of each of the enzymes of the complex. (NAD nicotinamide adenine dinucleotide FAD, flavin adenine dinucleotide TDP, thiamin diphosphate.)...

NAAb Natural autoantibody NAb Natural antibody NAC N-acetylcysteine NADH Reduced nicotinamide adenine dinucleotide NADP Nicotinamide adenine diphosphate... 

Nicotinamide adenine dinucleotide (NAD) Fructose 1,6-diphosphate Glucose-6-phosphate Isopentenyl pyrophosphate Ribose-6-phosphate-l-pyrophosphate... 

Hence, the presence of light is essential for this step. In this reaction, chlorophyll, carotenoids, and several other pigments that are organized in clusters absorb light energy and store it in the form of ATP and nicotinamide adenine diphosphate (NADP) in its reduced state (NADPH). 

In the past decade, a large number of studies emphasized the heterogeneous scale-free degree distribution of metabolic networks Most substrates participate in only a few reactions, whereas a small number of metabolites ( hubs ) participate in a very large number of reactions [19,45,52]. Not surprisingly, the list of highly connected metabolites is headed by the ubiquitous cofactors, such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), and nicotinamide adenine dinucleotide (NAD) in its various forms, as well as by intermediates of glycolysis and the tricarboxylic acid (TCA) cycle. 

NADPH nicotinamide adenine diphosphate phosphate reduced... 

FIGURE 1.4 Proposed biosynthetic route for the biosynthesis of (A) squalene oxide (squalene-2,3-oxide) via the isoprenoid pathway and (B) triterpene saponins of the dammarane-type and oleanane-type from squalene oxide. PP, diphosphate group GPS, geranyl phosphate synthase FPS, farnesyl phosphate synthase NADPH, nicotinamide adenine dinucleotide phosphate. 

Figure 6.1 Pathways involved in glucose oxidation by plant cells (a) glycolysis, (b) Krebs cycle, (c) mitochondrial cytochrome chain. Under anoxic conditions. Reactions 1, 2 and 3 of glycolysis are catalysed by lactate dehydrogenase, pyruvate decarboxylase and alcohol dehydrogenase, respectively. ATP and ADP, adenosine tri- and diphosphate NAD and NADHa, oxidized and reduced forms of nicotinamide adenine dinucleotide PGA, phosphoglyceraldehyde PEP, phosphoenolpyruvate Acetyl-CoA, acetyl coenzyme A FP, flavoprotein cyt, cytochrome e, electron. (Modified from Fitter and Hay, 2002). Reprinted with permission from Elsevier...

The sirtuins (silent information regulator 2-related proteins class III HDACs) form a specific class of histone deacetylases. First, they do not share any sequence or structural homology with the other HDACs. Second, they do not require zinc for activity, but rather use the oxidized form of nicotinamide adenine dinucleotide (NAD ) as cofactor. The reaction catalyzed by these enzymes is the conversion of histones acetylated at specific lysine residues into deacetylated histones, the other products of the reaction being nicotinamide and the metabolite 2 -0-acetyl-adenosine diphosphate ribose (OAADPR) [51, 52]. As HATs and other HDACs, sirtuins not only use acetylated histones as substrates but can also deacetylate other proteins. Intriguingly, some sirtuins do not display any deacetylase activity but act as ADP-ribosyl transferases. 

This enzyme [EC 2.7.7.1], also known as NAD pyropho-sphorylase, catalyzes the reaction of ATP with nicotinamide ribonucleotide to produce NAD+ and pyrophosphate (or, diphosphate). Nicotinate nucleotide is also a substrate. Nicotinate-nucleotide adenylyltransferase [EC 2.7.7.18] uses nicotinate ribonucleotide as the pyridine substrate, thereby producing deamido-NAD and pyrophosphate. 

This enzyme [EC 2.4.2.30] (also referred to as NAD+ ADP-ribosyltransferase, poly(ADP) polymerase, poly-(adenosine diphosphate ribose) polymerase, and ADP-ribosyltransferase (polymerizing)) catalyzes the reaction of NAD+ with [ADP-D-ribosyl] to produce nicotinamide and [ADP-D-ribosyl]( + i). The ADP-d-ribosyl group of NAD+ is transferred to an acceptor carboxyl group on a histone or on the enzyme itself, and further ADP-ribosyl groups are transferred to the 2 -position of the terminal adenosine moiety, building up a polymer with an average chain length of twenty to thirty units. 

Fig. 1. Energy metabolism in the normal myocardium (ATP adenosine-5 -triphosphate, ADP adenosine-5 -diphosphate, P phosphate, PDH pyruvate dehydrogenase complex, acetyl-CoA acetyl-coenzyme A, NADH and NAD" nicotinamide adenine dinucleotide (reduced and oxidized), FADH2 and FAD flavin adenine dinucleotide (reduced and oxidized).

Why do we need vitamins Early clues came in 1935 when nicotinamide was found in NAD+ by H. von Euler and associates and in NADP+ by Warburg and Christian. Two years later, K. Lohman and P. Schuster isolated pure cocarboxylase, a dialyz-able material required for decarboxylation of pyruvate by an enzyme from yeast. It was shown to be thiamin diphosphate (Fig. 15-3). Most of the water-soluble vitamins are converted into coenzymes or are covalently bound into active sites of enzymes. Some lipid-soluble vitamins have similar functions but others, such as vitamin D and some metabolites of vitamin A, act more like hormones, binding to receptors that control gene expression or other aspects of metabolism. 

Fig 2 Formation of morphine glucumnide. NAD = nicotinamide adenine dmuiteotidn NADH = reduced NAD ATP — adenosine triphosphate ADP = adenosine diphosphaie HIP = uridine triphosphate LrDP = undine diphosphate... 

FIGURE 21. Photosystem I (PS I). P700, special pair Q, plastoquinone QH2, dihy-droplastoquinone NADP, nicotinamide adenine dinucleotide phosphate FQR, ferre-doxin-quinone reductase FNR, ferredoxin-NADP reductase Fd, ferredoxin ADP, adenosine diphosphate ATP, adenosine triphosphate. 

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