NAD+

Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism.^[1] Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine nucleobase and the other, nicotinamide. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD⁺ and NADH (H for hydrogen), respectively.