<p>Members of this protein family, from both bacteria and eukaryotes, are the enzyme 3-hydroxyanthranilate 3,4-dioxygenase (<db_xref db="EC" dbkey="1.13.11.6"/>). It is part of the kynurenine pathway for the degradation of tryptophan and the biosynthesis of nicotinic acid [<cite idref="PUB00012238"/>].The prokaryotic homologue is involved in the 2-nitrobenzoate degradation pathway [<cite idref="PUB00012239"/>].</p><p>The enzyme acts on the tryptophan metabolite 3-hydroxyanthranilate and produces 2-amino-3-carboxymuconate semialdehyde, which can rearrange spontaneously to quinolinic acid and feed into nicotinamide biosynthesis, or undergo further enzymatic degradation.</p>