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Title: The Fe-heme structure of met-indoleamine 2,3-dioxygenase-2 determined by X-ray absorption fine structure

Highlights: • IDO2 is a newly discovered tryptophan metabolising enzyme with a role in immunity. • IDO2’s active site contains a heme moiety for tryptophan binding and catabolism. • EXAFS/XANES analysis provides the first data of an IDO2 Fe-heme environment. • IDO2 Fe-heme exists as a low spin bis(His) form at 10 K; mixed spin-state at RT. - 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 10 K, it exists in a low-spin bis(His) form with Fe–N{sub p}(av) = 1.97 Å, the Fe–N{sub Im} bond lengths of 2.11 Å and 2.05 Å, 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:
 [1] ;  [2] ;  [3] ;  [1] ;  [2] ; ;  [4] ;  [1]
  1. School of Chemistry, The University of Sydney, NSW 2006 (Australia)
  2. (Australia)
  3. (Japan)
  4. Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006 (Australia)
Publication Date:
OSTI Identifier:
22416614
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 450; Journal Issue: 1; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; BOND LENGTHS; CATABOLISM; CHEMICAL BONDS; EQUILIBRIUM; HEME; IMMUNITY; LIGANDS; MULTIPLE SCATTERING; OXYGENASES; SPIN; TEMPERATURE DEPENDENCE; TRYPTOPHAN; X-RAY SPECTROSCOPY