Tryptophan-2,3-Dioxygenase

• OMIM: 191070
• UniProt: P48775

Tryptophan -2 ,3- dioxygenase (TDO ) is an enzyme, the L-tryptophan oxidation by binding to two oxygen atoms. This is the first rate-limiting reaction and at the same step in the degradation of tryptophan. TDO is found in most living things. In humans, is primarily produced in the liver. An active TDO enzyme consists of a tetramer and binds two molecules of heme as a cofactor in the catalytic center.

TDO supplemented in the body with the indoleamine -2 ,3- dioxygenase ( IDO ), which catalyzes the same reductions; However, the IDO used instead of oxygen superoxide anions and is in the immune system and the placenta localized.

Catalyzed reaction

O2

L-tryptophan is oxidized to N- formyl-L- kynurenine. The Hämmolekül stabilizes the substrate ( tryptophan). The iron atom of the heme, as with all dioxygenases, involved in the oxidation of tryptophan. As a substrate, other tryptamines such as 5- hydroxytryptamine and serotonin are accepted.

Regulation

Transcription of TDO is influenced by the presence of glucocorticoids and heme. The enzyme activity of the TDO is modulated by insulin, and can be inhibited by the drugs acyclovir, tolmetin and sulindac.