Mediates electron transfer from NADH to oxygen, reducing it to water. This modular protein has 3 redox cofactors, in other organisms the same activity requires 2 or 3 proteins (By similarity). Binds 2 iron ions per subunit. By homology with NorV in E.coli, may be involved in nitric oxide detoxification. In the N-terminal section; belongs to the zinc metallo-hydrolase group 3 family. In the C-terminal section; belongs to the flavodoxin reductase family.