<p> This family describes NadN of <taxon tax_id="727">Haemophilus influenzae</taxon> and a small number of close homologs in pathogenic, Gram-negative bacteria. NadN is a periplasmic enzyme that cleaves NAD (nicotinamide adenine dinucleotide) to NMN (nicotinamide mononucleotide) and AMP. The NMN must be converted by a 5-nucleotidase to nicotinamide riboside for import. NadN belongs a large family of 5-nucleotidases and has NMN 5-nucleotidase activity for NMN, AMP, etc.</p> NAD pyrophosphatase/5-nucleotidase NadN