title: Purification and kinetic characterization of human indoleamine 2,3-dioxygenases 1 and 2 (IDO1 and IDO2) and discovery of selective IDO1 inhibitors.
abstract: Indoleamine 2,3-dioxygenase (IDO1) catalyzes the first step in tryptophan breakdown along the kynurenine pathway. Therapeutic inhibition of IDO1 is receiving much attention due to its proposed role in the pathogenesis of several diseases including cancer, hypotension and neurodegenerative disorders. A related enzyme, IDO2 has recently been described. We report the first purification and kinetic characterization of human IDO2 using a facile l-tryptophan consumption assay amenable to high throughput screening. We found that the K(m) of human IDO2 for l-tryptophan is much higher than that of IDO1. We also describe the identification and characterization of a new IDO1 inhibitor compound, Amg-1, by high throughput screening, and compare the inhibition profiles of IDO1 and IDO2 with Amg-1 and previously described compounds. Our data indicate that human IDO1 and IDO2 have different kinetic parameters and different inhibition profiles. Docking of Amg-1 and related analogs to the known structure of IDO1 and to homology-modeled IDO2 suggests possible rationales for the different inhibition profiles of IDO1 and IDO2.
authors.affiliation: Protein Sciences, Amgen Inc., Seattle, WA 98119, USA.
authors.forename: David
authors.initials: D
authors.lastname: Meininger
authors.forename: Leeanne
authors.initials: L
authors.lastname: Zalameda
authors.forename: Yichin
authors.initials: Y
authors.lastname: Liu
authors.forename: Lara P
authors.initials: LP
authors.lastname: Stepan
authors.forename: Luis
authors.initials: L
authors.lastname: Borges
authors.forename: John D
authors.initials: JD
authors.lastname: McCarter
authors.forename: Claire L
authors.initials: CL
authors.lastname: Sutherland
mesh_terms: D055808:Drug Discovery / Q000379:methods; D004791:Enzyme Inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D057166:High-Throughput Screening Assays; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; C576711:IDO2 protein, human; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007527:Isoenzymes; D011994:Recombinant Proteins