NADPH, the reduced nicotinamide adenine dinucleotide phosphate, plays an important role in many chemical reactions in organisms. It is a phosphorylated derivative of the 2' -site of the ribose ring of nicotinamide adenine dinucleotide (NAD+) linked to adenine. It participates in a variety of anabolic reactions, such as the synthesis of lipids, fatty acids and nucleotides, and can also provide energy for the fixation of carbon dioxide in the dark reaction. NADPH, the reduced form of NADP+, is required in these reactions as the reducing agent, the donor of the hydrogen negative ion.