title: The Fe-heme structure of met-indoleamine 2,3-dioxygenase-2 determined by X-ray absorption fine structure.
abstract: Multiple-scattering (MS) analysis of EXAFS data on met-indoleamine 2,3-dioxygenase-2 (IDO2) and analysis of XANES have provided the first direct structural information about the axial donor ligands of the iron center for this recently discovered protein. At 10K, it exists in a low-spin bis(His) form with Fe-Np(av)=1.97Å, the Fe-NIm bond lengths of 2.11Å and 2.05Å, which is in equilibrium with a high-spin form at room temperature. The bond distances in the low-spin form are consistent with other low-spin hemeproteins, as is the XANES spectrum, which is closer to that of the low-spin met-Lb than that of the high-spin met-Mb. The potential physiological role of this spin equilibrium is discussed.
authors.affiliation: School of Chemistry, The University of Sydney, NSW 2006, Australia; Australian Synchrotron, Clayton, Victoria 3168, Australia; Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Jade B
authors.initials: JB
authors.lastname: Aitken
authors.affiliation: School of Chemistry, The University of Sydney, NSW 2006, Australia; Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006, Australia.
authors.forename: Christopher J D
authors.initials: CJ
authors.lastname: Austin
authors.affiliation: Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006, Australia.
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Hunt
authors.affiliation: Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006, Australia.
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Ball
authors.affiliation: School of Chemistry, The University of Sydney, NSW 2006, Australia. Electronic address: peter.lay@sydney.edu.au.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Lay
mesh_terms: D003198:Computer Simulation; D006418:Heme / Q000737:chemistry*; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000737:chemistry* / Q000648:ultrastructure*; D007501:Iron / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation
chemical_list: C576711:IDO2 protein, human; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D006418:Heme; D007501:Iron
keywords: EXAFS; Heme environment; Indoleamine 2,3-dioxygenase-2 (IDO2); Mixed-spin species; X-ray absorption fine structure