NADP

(nicotinamide adenine dinucleotide phosphate, coenzyme II) A pyridine-based nucleotide that functions as a coenzyme to several different oxidoreductases. NADP usually acts as an electron donor in enzymatic reduction reactions; in this it differs from its counterpart *NAD , which acts principally as an electron acceptor in biological oxidations. NADP is sometimes called TPN, an abbreviation for its trivial name triphosphopyridine nucleotide. See also pentose phosphate pathway.