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Nicotinate and nicotinamide metabolism

Nicotinamide adenine dinucleotide
Skeletal formula of the oxidized form
Ball-and-stick model of the oxidized form
Names
Other names
Diphosphopyridine nucleotide (DPN+), Coenzyme I
Identifiers
3D model (Jmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.000.169
KEGG
PubChem CID
RTECS number UU3450000
UNII
Properties
C21H27N7O14P2
Molar mass 663.43 g/mol
Appearance White powder
Melting point 160 °C (320 °F; 433 K)
Hazards
Main hazards Not hazardous
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells. The compound is a dinucleotide, because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine base and the other nicotinamide. Nicotinamide adenine dinucleotide exists in two forms, an oxidized and reduced form abbreviated as NAD+ and NADH respectively.

In metabolism, nicotinamide adenine dinucleotide is involved in redox reactions, carrying electrons from one reaction to another. The coenzyme is, therefore, found in two forms in cells: NAD+ is an oxidizing agent – it accepts electrons from other molecules and becomes reduced. This reaction forms NADH, which can then be used as a reducing agent to donate electrons. These electron transfer reactions are the main function of NAD. However, it is also used in other cellular processes, the most notable one being a substrate of enzymes that add or remove chemical groups from proteins, in posttranslational modifications. Because of the importance of these functions, the enzymes involved in NAD metabolism are targets for drug discovery.

In organisms, NAD can be synthesized from simple building-blocks (de novo) from the amino acids tryptophan or aspartic acid. In an alternative fashion, more complex components of the coenzymes are taken up from food as the vitamin called niacin. Similar compounds are released by reactions that break down the structure of NAD. These preformed components then pass through a salvage pathway that recycles them back into the active form. Some NAD is also converted into nicotinamide adenine dinucleotide phosphate (NADP); the chemistry of this related coenzyme is similar to that of NAD, but it has different roles in metabolism.


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