Nicotinamide-adenine nucleotide, reduced NADH enzyme

Nicotinamide is an essential part of two important coenzymes nicotinamide adenine dinucleotide (NAD ) and nicotinamide adenine dinucleotide phosphate (NADP ) (Figure 18.19). The reduced forms of these coenzymes are NADH and NADPH. The nieotinamide eoenzymes (also known as pyridine nucleotides) are electron carriers. They play vital roles in a variety of enzyme-catalyzed oxidation-reduction reactions. (NAD is an electron acceptor in oxidative (catabolic) pathways and NADPH is an electron donor in reductive (biosynthetic) pathways.) These reactions involve direct transfer of hydride anion either to NAD(P) or from NAD(P)H. The enzymes that facilitate such... 

The technique has been used to separate breakdown products of reduced nicotinamide adenine dinucleotide (NADH) in acidic solution and to establish the reaction mechanism (415). It has also been used to monitor enzyme rates of reaction when at least one reactant is a nucleotide (416-418). 

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