A coenzyme that contains adenosine, nicotinamide, and phosphoric acid. When in its oxidized form (NADP1), it serves as an electron carrier in catabolic and anabolic reactions. In its reduced form (NADPH or NADPH-diaphorase), it is important in reducing the ferric iron (Fe+++) to its ferrous (Fe++) form, thus converting methemoglobin (which is unable to transport oxygen) to hemoglobin (which can transport oxygen). Deficiency of NADPH-diaphorase causes congenital methemoglobinemia.
A ubiquitous coenzyme present in all living cells which serves as a hydrogen transporter.