The function of Ensembl gene identifier ENSG00000151790 (TDO2, tryptophan 2,3-dioxygenase) is as follows. Heme-dependent dioxygenase that catalyzes the oxidative cleavage of the L-tryptophan (L-Trp) pyrrole ring and converts L- tryptophan to N-formyl-L-kynurenine. Catalyzes the oxidative cleavage of the indole moiety. {ECO:0000255|HAMAP-Rule:MF_03020, ECO:0000269|PubMed:25066423, ECO:0000269|PubMed:27762317, ECO:0000269|PubMed:28285122}.