Oxidoreductase FAD-binding domain

The oxidoreductase FAD-binding domain is an evolutionary conserved protein domain. To date, the 3D-structures of the flavoprotein domain of Zea mays nitrate reductase^[1] and of pig NADH:cytochrome b5 reductase^[2] have been solved. The overall fold is similar to that of ferredoxin:NADP⁺ reductase:^[3] the FAD-binding domain (N-terminal) has the topology of an anti-parallel beta-barrel, while the NAD(P)-binding domain (C-terminal) has the topology of a classical pyridine dinucleotide-binding fold (i.e. a central parallel beta-sheet flanked by 2 helices on each side).