<p>This family represents HemN, the oxygen-independent coproporphyrinogen III oxidase that replaces HemF function under anaerobic conditions. HemN catalyses the anaerobic transformation of coproporhyrinogen-III into protoporphyrinogen-IX during porphyrin biosynthesis. Several species, including <taxon tax_id="562">Escherichia coli</taxon>, <taxon tax_id="210">Helicobacter pylori</taxon>, and <taxon tax_id="63363">Aquifex aeolicus</taxon>, have both a member of this family and a member of another, closely related family for which there is no evidence of coproporphyrinogen III oxidase activity, <db_xref db="INTERPRO" dbkey="IPR004559"/>. Members of this family have a perfectly conserved motif PYRT[SC]YP in a region N-terminal to the region of homology with the related uncharacterised protein.</p>