<p>Pyridoxamine 5'-phosphate oxidase (<db_xref db="EC" dbkey="1.4.3.5"/>) is an enzyme that is involved in the de novo synthesis of pyridoxine (vitamin B6) and pyridoxal phosphate. It oxidizes pyridoxamine-5-P (PMP) and pyridoxine-5-P (PNP) to pyridoxal-5-P. The enzyme requires the presence of flavin mononucleotide (FMN) as a cofactor, although there is some evidence that coenzyme F420 may perform this role in some species [<cite idref="PUB00055044"/>].</p><p>The sequences of the enzyme from bacterial (genes pdxH or fprA) [<cite idref="PUB00002199"/>] andfungal (gene PDX3) [<cite idref="PUB00002264"/>] sources show that this protein has been highly conserved throughout evolution. PdxH is evolutionary related [<cite idref="PUB00001735"/>] to one of the enzymes in the phenazine biosynthesis protein pathway, phzD (also known as phzG).</p><p>This entry represents one of the two dimerisation regions of the protein, located at the edge of the dimer interface, at the C terminus, being the last three beta strands, S6, S7, and S8 along with the last three residues to the end. In <db_xref db="SWISSPROT" dbkey="P21159"/>, S6 runs from residues 178-192, S7 from 200-206 and S8 from 211-215. the extended loop, of residues 167-177 may well be involved in the pocket formed between the two dimers that positions the FMN molecule [<cite idref="PUB00024258"/>]. </p>