Enables several functions, including heme binding activity; oxygen binding activity; and tryptophan 2,3-dioxygenase activity. Involved in response to nitroglycerin and tryptophan catabolic process to acetyl-CoA. Human ortholog(s) of this gene implicated in Gilles de la Tourette syndrome and familial hypertryptophanemia. Orthologous to human TDO2 (tryptophan 2,3-dioxygenase). [provided by Alliance of Genome Resources, Apr 2022]