 This species could represent the active oxidant, or it could undergo hemolytic O-O bond cleavage to yield an iron(V)-oxo intermediate as the working oxidizing agent.The Rieske dioxygenase are a powerful class of redox-active enzymes, and reactions such as sulfoxidation, desaturation, and benzylic oxidation have been reported in addition to dioxygenation.While most iron-dependent dioxygenases utilize a non-heme iron cofactor, the oxidation of L-(and D-)tryptophan to N-formylkynurenine is catalyzed by either tryptophan 2,3-dioxygenase (TDO) or indoleamine 2,3-dioxygenase (IDO), which are heme dioxygenases that utilize iron coordinated by a heme B prosthetic group.