Anaerobic nitric oxide reductase; uses NADH to detoxify nitric oxide (NO), protecting several 4Fe-4S NO-sensitive enzymes. Has at least 2 reductase partners, only one of which (NorW, flavorubredoxin reductase) has been identified. NO probably binds to the di-iron center. Also able to function as an aerobic oxygen reductase (By similarity). Binds 3 Fe cations per monomer. Nitrogen metabolism; nitric oxide reduction. Homotetramer. In the N-terminal section; belongs to the zinc metallo-hydrolase group 3 family. This protein is missing the flavodoxin-like domain seen in orthologs.