This entry represents two-domain flavohemoproteins. These proteins have multiple enzymatic activities and consist of two distinct domains - an N-terminal heme- and oxygen-binding domain, and a C-terminal FAD and reductase domain. They display dihydropteridine reductase 2 activity, as well as functioning as nitric oxide dioxygenase and a ferrisiderophore reductase whereby the complexed Fe+3 iron of siderophores are reduced to Fe+2 and released.Flavohemoproteins are found in bacteria and fungi. They are involved in the inducible response to nitrosative stress, as their nitric oxide dioxygenase ability is used in aerobic NO detoxification, a reaction which utilises O2 and NAD(P)H to convert NO to nitrate and therefore offers protection from various noxious nitrogen compounds.