Oxidoreductases are enzymes that catalyze the transfer of a hydride ion between a substrate and a cofactor, in many cases, particularly those in metabolic reactions, that cofator is a form of nicotinamide adenine dinucleotide. Nicotinamide adenine dinucleotide phosphate (NADPH) is used in anabolic reactions while nicotinamide adenine dinucleotide (NAD+) is used in catabolic reactions.