<p> Pyridoxamine 5'-phosphate oxidase (PNPOx; <db_xref db="EC" dbkey="1.4.3.5"/>) is a FMN flavoprotein that catalyses the oxidation of pyridoxamine-5-P (PMP) and pyridoxine-5-P (PNP) to pyridoxal-5-P (PLP). This reaction serves as the terminal step in the de novo biosynthesis of PLP in Escherichia coli and as a part of the salvage pathway of this coenzyme in both E. coli and mammalian cells [<cite idref="PUB00016343"/>, <cite idref="PUB00016342"/>]. The binding sites for FMN and for substrate have been highly conserved throughout evolution.</p><p> This entry represents the FMN-binding domain present in pyridoxamine 5'-phosphate oxidases, as well as in a number of proteins that have not been demonstrated to have enzymatic activity. The FMN-binding domain has a structure consisting of a beta-barrel with Greek key topology, and is related to the ferredoxin reductase-like FAD-binding domain. PNPOx has a different dimerisation mode than that found in flavin reductases, which also carry an FMN-binding domain with a similar topology. </p> Pyridoxamine 5'-phosphate oxidase-like, FMN-binding domain