Nicotine adenine dinucleotide reduction

It appears to be well established by now that the reductant responsible for the conversion of vanadate(V) to oxovanadium(IV) is nicotine adenine dinucleotide phosphate (NADPH), produced in the pentose phosphate pathway.PI Further reduction to in the vacuoles of the vanadocytes of Phlebobranchia ascidians remains elusive. Several reductants have been proposed and shown to be effective in the in vitro and/or in vivo reduction of to V and/or to including tunichromes. Selected investigations of the related redox chemistry of vanadium can be briefly summarised as follows ... 

Some oxidoreductases require nicotine adenine dinucleotide (NADH) as a cofactor.146 To use them in organic synthesis, as in the reduction of a ketone to an alcohol, it is necessary to have an efficient system to continuously regenerate them. A common way is to include in the same reaction formic acid and formate dehydrogenase, the byproduct being carbon dioxide.147 The regeneration of the cofactor can also be done electrochemically with or without the addition of a hydrogenase.148 The use of whole organisms eliminates this need. 

The pyridine ring plays a key role in several biological processes, most notably in the oxidation/reduction coenzyme nicotine adenine dinucleotide (NADP) the vitamin niacin (or the corresponding acid) is required for its biosynthesis. Pyridoxine (vitamin Bg) plays a key role as the coenzyme in transaminases. Nicotine, a highly toxic alkaloid, is the major active component in tobacco, and the most addictive drug known. ... 

Thymidine monophosphate (deoxythymidine monophosphate [dTMP]) is generated from deoxyuridine monophosphate (dUMP). The methyl group added to the ring is derived from the CIO methylene unit of tetrahydrofolate as described in Chapter 12 (Scheme 12.9), and reduction is brought about by nicotine adenine dinucleotide (NADH, NAD+). A representation of the process is provided in Scheme 14.12. 

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. ... 

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... 

NAD A Coenzyme Nicotinamide adenine dinucleotide (NAD) is one of the principal oxidation-reduction reagents in biological systems. This nucleotide has the structure of two D-ribose rings (a dmucleotide) linked by their 5 phosphates. The aglycone of one ribose is nicotinamide, and the aglycone of the other is adenine. A dietary deficiency of nicotinic acid (niacin) leads to the disease called pellagra, caused by the inability to synthesize enough nicotinamide adenine dinucleotide. 

Nicotinic acid (niacin) Nicotinamide adenine dinucleotide (NAD+) Oxidation-reduction Pellagra (dermatitis, depression, diarrhea)... 

The answer is d. (Murray, pp 627-661. Scriver, pp 3897-3964. Sack, pp 121-138. Wilson, pp 287-320.) The vitamin whose structure appears in the question is nicotinic acid (niacin), which gives rise to the nicotinamide adenine dinucleotide coenzymes NAD and NADP. NAD is a cofactor required by all dehydrogenases. NADPII is a cofactor produced by the pentose phosphate shunt. It is utilized in reductive synthesis of compounds such as fatty acids. 

Figure 3.8. Structures of vitamins or vitamin-derived molecules that function in oxidation-reduction reactions. The oxidation of these redox groups in the inner mitochondricil membrane contributes to the electron transport chain that carries electrons from the oxidation of glucose to oxygen and in the process pumps protons from one side to the other of the inner mitochondrial membrane (see Chapter 8 for details). The proton gradient thus formed is used to phosphorylate ADP to form 32 of the 36 ATPs resulting from the oxidation of one glucose molecule to six CO2 and six H2O molecules. A Vitamin B3, also called niacin or nicotinic acid, becomes converted to the amide (nicotinamide) and dressed up with a ribose sugar. Then, in a manner like that of riboflavin in B becomes phosphorylated to form nicotinamide mononucleotide (NMN) or further reacted with the addition of adenosine monophosphate (AMP) to form nicotinamide adenine dinucleotide (NAD). B Vitamin B2, also known as riboflavin, is shown converted to the forms involved in redox reactions such as those of the electron transport chain. (From Biochemistry, Second Edition, D. Voet and J. Voet, Copyright 1995, John Wiley Sons, New York. Reprinted with permission of John Wiley Sons, Inc.)...

Niacin, also known as vitamin B3, nicotinic acid or vitamin PP, is a water-soluble B-complex vitamin (Table 7.1). This vitamin is the generic descriptor for two vitamers niacin and niacinamide. In the research literature the terms nicotinic acid/nicotinamide are most commonly used, while in medical practice niacin/niadnamide are preferred. The vitamin is obtained from the diet in the form of nicotinic acid, nicotinamide and tryptophan, which are transformed to nicotinamide adenine dinucleotides, NAD and NADP. These compounds participate in cellular oxidation-reduction reactions that are critical for energy production. NAD and NADP also participate in a wide variety of... 

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