. "Catalyzes, together with EC 1.13.11.52, the first and rate-limiting step in the kynurenine pathway, the major pathway of tryptophan metabolism." . "Specific for tryptophan as substrate, but is far more active with L-tryptophan than with D-tryptophan." . . . "Tryptophan 2,3-dioxygenase" . "Tryptamin 2,3-dioxygenase" . "Tryptophan oxygenase" . "Tryptophan pyrrolase" . "Tryptophanase" . "Indoleamine 2,3-dioxygenase" . "Indolamine 2,3-dioxygenase" . "L-tryptophan 2,3-dioxygenase" . "L-tryptophan pyrrolase" . "Tryptamine 2,3-dioxygenase" . "Tryptophan peroxidase" . . . "L-tryptophan + O(2) = N-formyl-L-kynurenine." . "Heme" .