Diphosphopyridine nucleotide,

P-Nicotinamide adenine dinucleotide reduced di-Na salt trihydrate (reduced diphosphopyridine nucleotide sodium salt, NADH) [606-68-8] M 763.5, pK as for NAD. 

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. 

The reduced form of diphosphopyridine nucleotide (DPNH), which is used in the reduction of di-O-phosphoglyceronic acid to O-phosphoglycerose, could be regenerated with high efficiency from the oxidized form (DPN ) by the reduced form of 6-thioctic acid, thus supplying the necessary re-... 

N4. Nordin, J. H., and Bretthauer, R. K., Colorimetric detection of carriers of galactosemia based on thionicotinamide diphosphopyridine nucleotide (TNDPN) reduction. Federation Proc. 20, 256 (1961). 

J. Preiss, P. Handler, Biosynthesis of Diphosphopyridine Nucleotides. I. Identification of Intermediates , J. Biol. them. 1958, 233, 488-492... 

The reduction of aromatic nitro compQunds (see p. 98) is also due to the action of an enzyme system in which a dehydrogenase transfers hydrogen to a diphosphopyridine nucleotide-flavoprotein, which in turn reduces the nitro group (Westfall, as well as Bueding and Jolliffe ). 

Diphosphopyridine nucleotide (NAD, DPN) see 3-nicotinamide adenine dinucleotide (diphosphopyridine nucleotide entry in Chapter 5. 

Nicotinamide adenine dinucleotide reduced disodium salt trihydrate (reduced diphosphopyridine nucleotide sodium salt, NADH) [606-68-8/ M 763.5. This coenzyme is available in high purity and it is advised to buy a fresh preparation rather than to purify an old sample as purification will invariably lead to a more impure sample contaminated with the oxidised form (NAD). It has... 

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... 

The reduced form of the respiratory coenzyme diphosphopyridine nucleotide (DPNH), which is vitally important for all cellular metabolism, is changed by dilute acid to a substance that, in the light of the following model experiments, may be a covalent hydrate. The 1,4-and 1,6-dihydro derivatives of l-benzylpyridine-3-carboxamide furnish a single substance when dissolved in dilute acid at 20° and the solution is basified. The stable yellow product, which has a prominent peak at 292 nm, was assigned the constitution 1-benzyl-6-hydroxy-1,4,5,6-tetra-hydropyridine-3-carboxamide61 (see Scheme 2). 3-Acetyl-1 -benzyl- 1,4-... 

Increased interest is added to the topic of this review by the discovery of several examples of covalent hydration in nature although no systematic investigation has been made, an increasing alertness to its possible occurrence can be detected among natural product workers. Some naturally occurring pteridines, such as xanthopterin,67 are covalently hydrated. The hydration of uracil and of the coenzyme diphosphopyridine nucleotide (DPNH) were mentioned in Section IV. 

The splitting of sugar to lactic acid is thus, briefly, the shifting of hydrogen by means of the nicotinamide moiety of diphosphopyridine nucleotide (also termed nicotinamide adenine dinuclcotide). Nicotinamide in DPN takes away two atoms of hydrogen from phosphorylated carbohydrate, and after dephosphorylation gives back two hydrogens fin DPNH ) to pyruvic acid. 

Ascorbic acid depleted from adrenal cortex or ovary on progesterone formation Niacin diphosphopyridine nucleotide (DPN) involved in progesterone synthesis... 

The toxic action of bilirubin on tissue metabolism has been demonstrated both by in vitro and in vivo experiments. Lathe (LI) added bilirubin to brain brei, in concentrations such as occur in hemolytic disease of the newborn and prematurity, and observed a decrease in oxygen consumption. Day (D3) was able to reverse this depressed respiration by the addition of cytochrome c or methylene blue. Bowen and Waters (B16) then showed that this reversal could also be efFected by diphosphopyridine nucleotide. Zetterstrom and Ernster (Zl), using isolated rat liver mitochondria, showed that bilirubin in concentrations... 

Boyer, P.D. and Theorell, H. The change in reduced diphosphopyridine nucleotide (DPNH) fluorescence upon combination with liver alcohol dehydrogenase (ADH). Acta Chem. Scand., 10 447-450, 1956. 

Winer, A.D., Schwert, G.W. and Millar, D.B.S. Lactic dehydrogenase. VI. Fluorometric measurements of the complex of enzyme and reduced diphosphopyridine nucleotide. 

The conversion of 3-deoxy-D-am6mo-heptulosonic acid 7-phosphate to 5-dehydroquinate was also abolished by the chelating agent (ethylenedi-nitrilo)tetracetate, and could be restored partially by Zn and completely by Co . Occasionally, carbon-treated preparations could not be reactivated by diphosphopyridine nucleotide alone only by the further addition of cobaltous salts was activity restored. Attempts to acciunulate an intermediate by omitting, from such extracts, either diphosphop dine nucleotide or Co were not successful, and, unless both of these were simultaneously present, the 3-deoxy-D-oroWno-heptulosonic acid 7-phosphate remained xmchanged. 

Fio. 7.—Tentative Mechanism for the Enzymic Conversion of 3-Deoxy-n-aro5mo-heptulosonic Acid 7-Phoaphate to 6-Dehydroquinic Acid. (DPN denotes diphosphopyridine nucleotide and DPNH is reduced diphosphopyridine nucleotide.)... 

The ring of anthranilic acid, like that of prephenic acid, is derived, in appropriate bacterial extracts, from shikimate 5-phosphate, the amino group originating in the amide nitrogen of glutamine. An oxidation-reduction appears to be involved in this synthesis, since diphosphopyridine nucleotide is a required cofactor. At least one other cofactor, present in yeast extract and so far unidentified, is also required. 

The nicotinamide coenzymes are involved as proton and electron carriers in a wide variety of oxidation and reduction reactions. Before their chemical structures were known, NAD and NADP were known as coenzymes I and II. Later, when the chemical nature of the pyridine ring of nicotinamide was discovered, they were called diphosphopyridine nucleotide (DPN = NAD) and triphospho-pyridine nucleotide (TPN = NADP). The nicotinamide nucleotide coenzymes are sometimes referred to as the pyridine nucleotide coenzymes. 

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