Amidation of deamino-NAD+ to NAD+ EC Number: 6.3.5.1 NAD synthase catalyzes the final step in the biosynthesis of NAD+, both in the de novo synthesis and in the salvage pathways. The enzyme makes use of glutamine as an amide donor in the reaction. NAD synthase exists as a homohexamer in the cytosol. There are two forms of NAD synthase in humans, NADsyn1 and NADsyn2. The major difference between the two forms is that NADsyn1 appears to be glutamine-dependent whereas NADsyn2 is strictly ammonia-dependent. Pubmed12547821 Reactome Database ID Release 43197271 Reactome, http://www.reactome.org ReactomeREACT_11135