Nicotinamide adenine dinucleotide phosphate, abbreviated NADP+ or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent, as well as cholesterol synthesis, and fatty acid chain elongation. NADP is an electron acceptor. NADPH is the reduced form of NADP+.
NADP+ differs from NAD+ in the presence of an additional phosphate group on the 2′ position of the ribose ring that carries the adenine moiety. β-Nicotinamide adenine dinucleotide 2′-phosphate (NADP+) and β-Nicotinamide adenine dinucleotide 2′-phosphate, reduced (NADPH) comprise a coenzyme redox pair (NADP+:NADPH) involved in a wide range of enzyme catalyzed oxidation reduction reactions. The NADP+/NADPH redox pair is used in a variety of anti-oxidation mechanism where it protects against reactive oxidation species accumulation.
The NADPH system is also responsible for generating free radicals in immune cells. These radicals are used to destroy pathogens in a process termed “respiratory burst” (or “oxidative burst”).
NADPH provides the reducing equivalents for biosynthetic reactions and the oxidation-reduction involved in protecting against the toxicity of ROS (reactive oxygen species), allowing the regeneration of GSH (reduced glutathione).
NADPH is also used for anabolic pathways, such as lipid synthesis, cholesterol synthesis, and fatty acid chain elongation.