A coenzyme and an important component of the enzymatic systems concerned with biological oxidation-reduction systems. It is also known as NAD, triphosphopyridine nucleotide (TPN), coenzyme II, and codehydrogenase II. The compound is similar in structure and function to nicotinamide adenine dinucleotide (NAD). It differs structurally from NAD in having an additional phosphoric acid group esterified at the 2′ position of the ribose moiety of the adenylic acid portion. In biological oxidation-reduction reactions the NADP molecule becomes alternately reduced to its hydrogenated form (NADPH) and reoxidized to its initial state (see illustration). See Carbohydrate metabolism, Coenzyme, Enzyme
(NADP; also called triphosphopyridine nucleotide, or TPN; obsolete term, coenzyme II and codehydrogenase II), a common coenzyme. Like nicotinamide adenine dinucleotide, NADP is found in all types of cells, where it participates in oxidation-reduction reactions. Its structure was established in 1934 by O. Warburg. It serves as a hydrogen acceptor during the oxidation mainly of carbohydrates; in its reduced form it is a hydrogen donor during the biosynthesis of fatty acids. In the chloroplasts of plant cells, NADP is reduced during the light reactions of photosynthesis and then provides hydrogen for the synthesis of carbohydrates during dark reactions.