Nicotinamide adenine dinucleotide is a cofactor that is central to metabolism. Found in all living cells, NAD is called a
dinucleotide because it consists of two nucleotides joined through their phosphategroups. One nucleotide contains an adenine nucleobase and the other nicotinamide. NAD exists in twoforms: an oxidized and reduced form, abbreviated as NAD+ and NADH respectively.
