Nicotinamide adenine dinucleotide (NAD)

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.

In metabolism, nicotinamide adenine dinucleotide is involved in redox reactions, carrying electrons from one reaction to another. These electron transfer reactions are the main function of NAD. However, it is also used in other cellular processes, most notably a substrate of enzymes that add or remove chemical groups from proteins, in posttranslational modifications.