NAD+ structure

NAD+ (structure 8.11, R = H) and NADP+ (structure 8.11, R = P03 ) function as coenzymes in redox reactions by reversibly accepting hydrogen at the 4 position of the nicotinamide ring (equation 8.12). 

Figure 7.21. (a) The Nad structure using P and O sites. (b) The sites of both T layers, (c) The 3-4PTOT structure of K3C6o- The Q,o molecules are in P sites with K in O (open circles) and T (filled circles) sites. 

All of the alkaline earth oxides, MO, except one crystallize in the rock salt (Nad) structure. What is the exception and what is the likely structure for it (Wells, A. F. Structural Inorganic Chemistry, 5th ecL Oxford University Oxford, 1984.)... 

Figure 12 Structure of 7a-HSDH from E. coli. (a) Overall structure of 7a-HSDH in complex with NAD and the product 7-oxoglycochenodeoxycholic acid (70GD). The substrate-binding loop in the binary enzyme NAD" structure is shown in light orange, (b) Interaction of the three conserved active site residues and the two ligands. The pdb files used were 1 ahh and lahi, and the figure was made with PyMOL. ...

Arthur Harden and William J. Young (see chapter 1) showed three decades earlier that the fermentation enzyme in yeast is separable into a colloidal fraction ( zymase ) and a heat-stable, water-soluble fraction ( cozymase ). Tbe two fractions separately show no enzymatic activity. Warburg later demonstrated the activity of cozymase and, in 1936, nicotinic acid (niacin or vitamin Bj) was found to be its hydrolysis byproduct. In that year, Hans von Euler-Chelpin published the structure of nicotinamide adenosine dinucleotide (NAD ) and its phosphate derivative (NADP ) (see the structure below). Euler-Chelpin shared the 1929 Nobel Prize in chemistry with Arthur Harden for their independent studies on cozymase, seven years before publication of the NAD structure. In contrast to FMN and FAD, NAD, and NADP only transfer two electrons (H + 2e") at a time (see the structure below). 

FIGURE 15 5 Structure of NAD the oxidized form of the coenzyme nicotinamide adenine dinucleotide The functional part of the coen zyme is framed in red... 

Oxidation of P-nicotinamide adenine dinucleotide (NADH) to NAD+ has attracted much interest from the viewpoint of its role in biosensors reactions. It has been reported that several quinone derivatives and polymerized redox dyes, such as phenoxazine and phenothiazine derivatives, possess catalytic activities for the oxidation of NADH and have been used for dehydrogenase biosensors development [1, 2]. Flavins (contain in chemical structure isoalloxazine ring) are the prosthetic groups responsible for NAD+/NADH conversion in the active sites of some dehydrogenase enzymes. Upon the electropolymerization of flavin derivatives, the effective catalysts of NAD+/NADH regeneration, which mimic the NADH-dehydrogenase activity, would be synthesized [3]. 

The only selenium diimide to be structurally characterized in the solid state, Se(NAd)2 (Ad = adamantyl), ° adopts the cis, trans conformation consistent with conclusions based on H and C NMR studies for Se(N Bu)2. ... 

FIGURE 18.19 The structures and redox states of the nicotinamide coenzymes. Hydride ion (H , a proton with two electrons) transfers to NAD to produce NADH. 

FIGURE 20,20 (a) The structure of malate dehydrogenase, (b) The active site of malate dehydrogenase. Malate is shown in red NAD" is blue. 

The crystal structure of the halohydrin dehalogenase from the soil bacterium Agrobacterium radiobacter ADI, HheC, has been solved [129]. HheC is structurally related to the family of NAD(P)H-dependent short-chain dehydrogenases/reduc-... 

Nicotinamide and nicotinic acid are both white crystalline substances. Their aqueous solution has a maximal UV absorbance at 263 nm. Both vitamers have the same biological activity as they can be converted into each other. Figure 2 shows the structure of the coenzyme forms NAD+ and NADP+. 

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

The functions of a large proportion of the proteins encoded by the human genome are presently unknown. Recent advances in bioinformatics permit researchers to compare amino acid sequences to discover clues to potential properties, physiologic roles, and mechanisms of action of proteins. Algorithms exploit the tendency of nature to employ variations of a structural theme to perform similar functions in several proteins (eg, the Rossmarm nucleotide binding fold to bind NAD(P)H,... 

D-Ribose Nucleic acids. Structural elements of nucleic acids and coenzymes, eg, ATP, NAD, NADP, flavo-proteins. Ribose phosphates are intermediates in pentose phosphate pathway. ... 

Zinc-containing alcohol dehydrogenases take up two electrons and a proton from alcohols in the form of a hydride. The hydride acceptor is usually NAD(P) (the oxidized form of nicotinamide adenine dinucleotide (NADH) or its phosphorylated derivative, NADPH). Several liver alcohol dehydrogenases have been structurally characterized, and Pig. 17.8 shows the environment around the catalytic Zn center and the bound NADH cofactor. 

Nagasawa T, Kikutani H, Kishimoto T. Molecular cloning and structure of a pre-B-cell growth-stimulating factor. Proc Nad Acad Sci U S A 1994 91(6) 2305-2309. 

FIGURE 20.1 Schematic illustration of lycopene metabolic pathway by CM02. (a) 5-cis Lycopene and 13-cis lycopene are preferentially cleaved by CM02 at 9, 10 -double bond. The cleavage product, apo-lO -lycopenal, can be further oxidized to apo-lO -lycopenol or reduced to apo-lO -lycopenoic acid, depending on the presence of NAD+ or NADH. (b) Chemical structures of apo-lO -lycopenoic acid, acyclo-retinoic acid, and all-frans retinoic acid. (Adapted from Hu, K.Q. et al., J. Biol. Chem., 281, 19327, 2006. With permission.)... 

Fig. 21.1 The interactions between the bound coenzyme molecule and the amino acids at positions 47 and 369 in the / , / 2, and / 3 polymorphic variants as observed in their respective structures determined by X-ray crystallography. The dashed lines indicate possible hydrogen-bonds between the amino acids and the phosphate oxygens of the bound coenzyme molecule, NAD(H). Arg47 is substituted by a His residue in the f 2 isozyme and Arg369 is substituted by a Cys residue in the / 3 isozyme. In each case, the substitution results in a net loss of hydrogen-bonding interactions and weaker affinity for the coenzyme.

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