Indoleamine 2,3-dioxygenase

Indoleamine 2,3-dioxygenases, or IDOs, are the main enzymes responsible for the metabolism of l-Tryptophan (Trp), and the open gate of the kynurenine pathway, where the majority of the intake of the essential amino acid is conveyed. The kynurenine pathway produces a great variety of molecules, involved in a great spectrum of physio-pathological mechanisms, spanning from the regulation of the immune response to neurodegenerative diseases, and from maternal-fetal tolerance to cancer. Hence, the understanding of IDOs’ biochemistry, with their fine regulation, represents a fundamental challenge to researchers. In this chapter, we reported the latest discoveries about IDOs also focusing on the development of drugs currently involved in clinical trials.