NADP p-Nicotinamide

NADP, p-nicotinamide adenine dinucleotide phosphate NADPH, reduced NADP... 

NAD P-nicotinamide-adenine dinucleotide, reduced form NADP P-nicotinamide-adenine dinucleotide phosphate, oxidized form... 

Fig. 4. The cycle of events involved in cytochrome (Cyt) P q (Cyt P450 Fe + ) mediated dmg metaboHsm where NADP is nicotinamide disphosphate and...

P-Nicotinamide adenine dinucleotide phosphate (NADP, TPN) [53-59-8] M 743.4, pKi 1.1 (PO4H2), pK2 4.0 (adenine NH2), PK3 6.1 (P04 ). Purified by anion-exchange chromatography in much the same way as for NAD [Dalziel and Dickinson Biochem 7 95 311 1965 Biochemical Preparations 11 87 1966]. Finally it is purified by dissolving in H2O and precipitating with 4 volumes of Me2CO and dried in... 

P-Nicotinamide adenine dinucleotide phosphate reduced tetrasodium salt (reduced diphosphopyridine nucleotide phosphate sodium salt, NADPH) [2646-71-1] M 833.4, pK as for NADP. Mostly similar to NADH above. 

Flora F-6-P = fructose-6-phosphat, NADP+/NADPh = nicotinamide adenosindinucleotide phosphate in oxidized and reduced form (under physiological conditions NADPH2 is deprotonized into NADPH + H+), PGA = phosphoglyceric acid, R-5-P = ribulose-5-phosphate, R-1.5-DP = ribulose-1,5-diphosphate,... 

BPDE benzo[a]pyrene diol epoxide B[a]P = benzo[a]pyrene DMSO = dimethyl sulfoxide ELISA = enzyme linked immunosorbent assay FI = fluorescence Gua = guanine GC/MS = gas chromatography/mass spectrometry HPLC = high-performance liquid chromatography NADP = oxidized nicotinamide adenosine dinucleotide ... 

Synthesis of NAD and NADP . The nicotinamide cofactors are now isolated from yeast (25,26). A major difficulty in this preparation is simply that of separation of the NAD(P)(H) from the other components in the cell. To reduce the cost of these materials, either the yield must be improved from the yeast preparation, the isolation must be simplified, or some type of synthesis must be developed. We have taken a step toward developing a new synthesis by the combined enzymatic/conventional synthetic procedure summarized in Figure 3(27). The overall conversion from... 

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... 

Several other electron-transfer reagents have been tested with arenediazonium ions, for example, A-benzyl-l,4-dihydronicotinamide, which is a model for biochemical reductions by NAD(P)H, the reduced form of NADP+ (nicotinamide adenine cfinucleotide phosphate) (Yasui et al., 1984). 

Until now, only a few versatile, selective and effective transition-metal complexes have been applied in nicotinamide cofactor reduction. The TOFs are well within the same order of magnitude for all systems studied, and are within the same range as reported for the hydrogenase enzyme thus, the catalytic efficiency is comparable. The most versatile complex Cp Rh(bpy) (9) stands out due to its acceptance of NAD+ and NADP+, acceptance of various redox equivalents (formate, hydrogen and electrons), and its high selectivity towards enzymatically active 1,4-NAD(P)H. 

Biochemical Effects Several enzymes that use nicotinamide cofactors were found to ye inhibited by PAN (at 125 ppm for 1 min) in in vitro studies. These enzymes were most susceptible in the absence of substrates. In some cases, an enzyme was protected by the nicotinamide cofactor (e.g., G-6-PD plus NADP), and in other cases, by the cosubstrate (e.g., isocitrate dehydrogenase plus isocitrate). Precisely the same protection could be obtained when compounds that react with sulfhydryl compounds (e.g., p-mercuricbenzoate) were used instead of PAN. Thus, the evidence indicated that PAN reacted with sulfhydryl groups. 

The pyridine nucleotides NAD and NADP always function in unbound form. The oxidized forms contain an aromatic nicotinamide ring in which the positive charge is delocalized. The right-hand example of the two resonance structures shown contains an electron-poor, positively charged C atom at the para position to nitrogen. If a hydride ion is added at this point (see above), the reduced forms NADH or NADPH arise. No radical intermediate steps occur. Because a proton is released at the same time, the reduced pyridine nucleotide coenzymes are correctly expressed as NAD(P)H+HT... 

This enzyme [EC 1.6.1.1] (also known as NAD(P)+ trans-hydrogenase (B-specific), pyridine nucleotide transhy-drogenase, and nicotinamide nucleotide transhydro-genase) catalyzes the reversible reaction of NADPH with NAD+ to produce NADP+ and NADH. This FAD-dependent enzyme is B-specific with respect to both pyridine coenzymes. In addition, deamino coenzymes will also serve as substrates. 

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... 

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. 

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