NADP+ nicotinamide adenine dinucleotide structure

Niacin. Figure 2 Structure of the coenzymes NAD+ (nicotinamide-adenine dinucleotid) and NADP+ (nicotinamide-adenine dinucleotid phosphate). 

On the other hand, NAD (nicotinamide adenine dinucleotide), known as coenzyme I and II, and NADP (nicotinamide adenine dinucleotide phosphate) are derivatives of nicotinamides. The chemical structures of NAD, NADP, and the reduced form of these alkaloids, NADH and NADPH (nicotinamide adenine dinucleotide phosphate reduced), are shown. Isonicotinic acid hydrazide (INH or isoniazid) is a synthetic derivative of nicotinic acid and has potent antibacterial activity against Mycobacterium tuberculosis (Section 13.2) [1,2]. 

Chemical structure (Figure 8). Nicotinic acid (pyridine-3-carboxylic acid), nicotinamide (pyridine-3-carboxamide), NAD (nicotinamide adenine dinucleotide), NADP (nicotinamide adenine dinucleotide phosphate). 

The second type of biological electron transfer involves a variety of small molecules, both organic and inorganic. Examples of these are (a) nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) as two electron carriers and (b) quinones and flavin mononucleotide (FMN), which may transfer one or two electrons. The structure of NAD and its reduced counterpart NADH are shown in Figure 1.12. 

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. ... 

An important aspect of enzymatic oxidation-reduction reactions involves the transfer of hydrogen atoms. This transfer is mediated by coenzymes (substances that act together with enzymes) nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These two species pick up H atoms to produce NADH and NADPH, respectively, both of which can function as hydrogen atom donors. Another pair of species involved in oxidation-reduction processes by hydrogen atom transfer consists of flavin adenine triphosphate (FAD) and its hydrogenated form FADH2. The structural formulas of NAD and its cationic form, NAD+, are shown in Figure 4.7. 

The vast majority of alcohol dehydrogenases require nicotanimide cofactors, such as nicotinamide adenine dinucleotide (NADH) and its respective phosphate NADPH. The structure of NAD/NADP is shown in Fig. 3.39. Hydrogen and two electrons are transferred from the reduced nicotinamide to the carbonyl group to effect a reduction of the substrate (see Fig. 3.39). 

Figure 14.13. Structures of the Oxidized Forms of Nicotiuamide-Derived Electrou Carriers. Nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+) are prominent carriers of high-energy electrons. In NAD+, R = H in NADP+, R = PO3 2-.

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. 

This reaction fixes carbon but there is no net change in oxidation number. The CO2 is reduced to carboxyl but one of the carbon atoms in the RuBP is oxidized to yield the second carboxyl group. In subsequent steps, each mole of PGA reacts with a mole of NADPH in order to produce two moles of 3-phosphoglyceraldehyde, a product in which average oxidation number of carbon is 0. NADPH is the reduced form of nicotinamide adenine dinucleotide phosphate (see any biochemistry text for structures and further details). In biosynthetic processes, it functions as a hydride donor or reductant. A typical reaction is shown below. Note that NADPH + H is equivalent to NADP + H2. 

For contrast and completeness, NAD and NADH should be introduced here. NAD is the oxidized form of nicotinamide adenine dinucleotide. It is structurally identical to NADP except that it lacks a phosphate group at a key point. Order and control are brought to biochemical oxidations and reductions by this seemingly trivial distinction. NAD is generally an oxidant. NADPH is generally a reductant. Each is present within a cell at only microscopic concentrations. Specialized mechanisms exist for the oxidation... 

Nicotinamide (34) and structurally related 51 compounds were subjected to the halting activity bioassay to elucidate the structure-activity relationships [105]. The highest activity was recorded in thionicotinamide (35) followed by pyrazinamide (36) and nicotinamide (34). Nicotinamide adenine dinucleotide (NAD) (oxidized form), nicotinamide adenine dinucleotide phosphate (NADP) (oxidized form), (3-nicotinamide mononucleotide (oxidized form) showed halting activity at ca. 10"7 M... 

Two nicotinamide coenzymes, jff-nicotinamide adenine dinucleotide (NAD" ) and jff-nicotinamide adenine dinucleotide phosphate (NADP" ), have closely related structures (Fig. 9.9) and electrochemical properties. Although generally represented as cations, it is worth pointing out that in both cases the oxidized forms of coenzymes are anionic at neutral pH due to ionization of phosphate groups in the... 

The vitamin niacin (section 11.8) is important for the formation of two closely related compounds, the nicotinamide nucleotide coenzymes — nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). As shown in Figure 2.16, they differ only in that NADP has an additional phosphate group attached to the ribose. The whole of the coenzyme molecule is essential for binding to enzymes, and most enzymes can bind and use only one of these two coenzymes, either NAD or NADP, despite the overall similarity in their structures. 

Nicotinamide adenine dinucleotide (NAD ) and nicotinamide adenine dinucleotide phosphate (NADP+) are structurally dinucleotides (Fig. 29). The two substances differ from each other by one phosphate residue, which is present in NADP" " and is attached to the 2 hydroxyl group of one of the ribose residues. The actual redox system is the nicotinamide which can be reversibly reduced, again by a 2 electron transition. Flavoproteins are very often coupled with NAD+or NADP+. In photosynthesis reduced FAD can transmit 2H (= 2e -)- 2H+) to NADP+, leading to NADPH -I- H+. 

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