Heme-dependent dioxygenases in tryptophan oxidation

- Tryptophan dioxygenase catalyzes the first and committed step in the kynurenine pathway.
- Recent progress of the enzymatic studies of tryptophan oxidation is summarized.
- Catalytic strategies are proposed to involve in high-valent Fe intermediates.
- Peroxide reaction with the ferric enzyme is important for the enzyme reactivation.