Nicotinic acid adenine dinucleotide (deamido-NAD NAAD) is a closely related analog of NAD. It is used to study the structure of nicotinate mononucleotide adenylyltransferase(s) (NMN/NaMN). NAAD is used as a substrate to study the specificity and kinetics of nicotinamide adenine dinucleotide synthetase(s) (NADS). In addition it is also used as a co-substrate to study mechanisms of members of the Sir2 class of NAD-dependent deacetylase.