Tryptophan 2,3-dioxygenase

TDO2
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	4PW8
Identifiers
Aliases	TDO2, TDO, TO, TPH2, TRPO, tryptophan 2,3-dioxygenase, HYPTRP
External IDs	OMIM: 191070; MGI: 1928486; HomoloGene: 4132; GeneCards: TDO2; OMA:TDO2 - orthologs
Gene location (Human)
Chr.	Chromosome 4 (human)
End	155,920,406 bp
Gene location (Mouse)
Chr.	Chromosome 3 (mouse)
End	81,883,509 bp
RNA expression pattern
	Top expressed in
	right lobe of liver; ; appendix; ; testicle; ; gonad; ; duodenum; ; lymph node; ; pituitary gland; ; gallbladder; ; anterior pituitary; ; rectum;
	Top expressed in
	gastrula; ; left lobe of liver; ; gallbladder; ; decidua; ; Ileal epithelium; ; yolk sac; ; embryo; ; dentate gyrus of hippocampal formation granule cell; ; lumbar subsegment of spinal cord; ; primitive streak;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	oxygen binding; oxidoreductase activity; protein binding; dioxygenase activity; amino acid binding; metal ion binding; identical protein binding; tryptophan 2,3-dioxygenase activity; heme binding;
Cellular component	cytosol;
Biological process	tryptophan catabolic process; tryptophan catabolic process to acetyl-CoA; tryptophan metabolic process; tryptophan catabolic process to kynurenine; protein homotetramerization; response to nitroglycerin;
	Sources:Amigo / QuickGO
Orthologs
	6999
	56720
	ENSG00000262635; ENSG00000151790
	ENSMUSG00000028011
	P48775
	P48776
	NM_005651
	NM_019911
	NP_005642
	NP_064295
	Wikidata
View/Edit Human	View/Edit Mouse

In enzymology, tryptophan 2,3-dioxygenase (EC 1.13.11.11) is a heme enzyme that catalyzes the oxidation of L-tryptophan (L-Trp) to N-formyl-L-kynurenine, as the first and rate-limiting step of the kynurenine pathway.

L-tryptophan + O₂ ⇌ N-formyl-L-kynurenine

Tryptophan 2,3-dioxygenase plays a central role in the physiological regulation of tryptophan flux in the human body, as part of the overall biological process of tryptophan metabolism. TDO catalyses the first and rate-limiting step of tryptophan degradation along the kynurenine pathway and thereby regulates systemic tryptophan levels. In humans, tryptophan 2,3-dioxygenase is encoded by the TDO2 gene.