English Tryptophan 2,3-dioxygenase Cited by user E L Raven on 12 Jan 2017 In enzymology, tryptophan 2,3-dioxygenase is a heme enzyme that catalyzes the oxidation of L-tryptophan (L-Trp) to N-formyl-L-kynurenine, as the first and rate-limiting…