Nicotinamide adenine dinucleotide

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 nucleobase and the other nicotinamide.

Pronunciation

Nicotinamide adenine dinucleotide: /ˌnɪkəˈtɪnəmaɪd ˈædənɪn daɪˈnjuːklɪəˌtaɪd/

Etymology

The term "Nicotinamide adenine dinucleotide" is derived from the components of the molecule itself. "Nicotinamide" is a compound formed from nicotinic acid and ammonia. "Adenine" is one of the two purine nucleobases used in forming nucleotides of the nucleic acids DNA and RNA. "Dinucleotide" refers to a type of molecule that consists of two nucleotides.

Function

NAD 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.

Related Terms

• NADP+: Nicotinamide adenine dinucleotide phosphate, a coenzyme used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent.
• NADH: The reduced form of NAD.
• NAD+: The oxidized form of NAD.
• Coenzyme: A non-protein compound that is necessary for the functioning of an enzyme.
• Redox: A type of chemical reaction that involves a transfer of electrons between two species.

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