Flavodoxin

Flavodoxin (FDX) is a bacterial protein which contains flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD). It participates in nitrogen metabolism and reduces N2 to NH3 while changing from its oxidized quinone state FDX-ox via semiquinone FDX-sq to its reduced hydroquinone state FDX-red^[1]. NrdI is a FDX which is involved in ribonucleotide reduction. WrbA (Tryptophan Repressor-Binding Protein) is also FDX. In E. coli there are 2 distinct flavodoxins: FDX I and II.