NADP, abbreviated as NADh+, is a coenzyme found in all living cells. This compound is a dinucleotide because it consists of two nucleotides connected by a phosphate group. One nucleotide contains an adenine base and the other contains nicotinamide.

 In metabolism, NAD+ participates in redox reactions, bringing electrons from one reaction to another. Therefore, coenzymes exist in two forms in cells: NAD+ is an oxidant-it accepts electrons from other molecules and is reduced. This reaction forms NADH (nicotinamide adenine dinucleotide), 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 is the substrate of enzymes, which add or remove chemical groups from proteins in post-translational modifications. Due to the importance of these functions, enzymes involved in NAD+ metabolism are the targets of drug discovery.
 
 In organisms, NADP can be synthesized (de novo) from simple structural units of the amino acids tryptophan or aspartic acid. In another way, the more complex components of coenzymes are taken from food as a vitamin called niacin. A reaction that breaks down the NAD+ structure releases similar compounds. These pre-formed components are then recycled through a recycling route to recover them back to their active form. Some NAD+ is also converted to nicotinamide adenine dinucleotide phosphate (NADP+); this related coenzyme has similar chemical properties to NAD+, but has a different role in metabolism