The Many Faces of Sirtuins: Coupling of NAD metabolism, sirtuins and lifespan

Nicotinamide adenine dinucleotide (NAD), a coenzyme found in all living cells, was discovered by Sir Arthur Harden as a molecular fraction that greatly accelerated alcoholic fermentation in yeast extract. Other biochemists have contributed to what we know today about NAD: it serves as an essential cofactor of many biochemical reactions, for example in glucose and fat oxidation reactions in its oxidized form (NAD+) or as a substrate for the electron transport chain in its reduced (NADH) form. In addition, NAD has a crucial role as a cofactor for other enzymes, including the protein deacetylases sirtuins, the poly-ADP-ribose polymerase (PARP) and the cyclic ADP-ribose hydrolase CD38.