Crystallization and preliminary crystallographic studies of human indoleamine 2,3-dioxygenase.

Indoleamine 2,3-dioxygenase (IDO) is a haem-containing dioxygenase that catalyzes the oxidative cleavage of the pyrrole ring of indoleamines by the insertion of molecular oxygen. This reaction is the first and the rate-limiting step in the kynurenine pathway, the major Trp catabolic pathway in mammals. Recombinant human IDO was crystallized by the vapour-diffusion technique. The addition of 4-phenylimidazole as a haem ligand was essential for crystallization. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 86.1, b = 98.0, c = 131.0 A. Diffraction data were collected to 2.3 A resolution.