4u74 | pdb_00004u74

Crystal structure of 4-phenylimidazole bound form of human indoleamine 2,3-dioxygenase (G262A mutant)

spinqualitylabelsall models 4u74, resolution 2.31Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4u74 is a 2 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM, NHE, PIM Related: 2d0t, 2d0u, 4u72 Gene: IDO1, IDO, INDO (HUMAN) Activity: Indoleamine 2,3-dioxygenase, with EC number 1.13.11.52 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [I23O1_HUMAN] Catalyzes the cleavage of the pyrrol ring of tryptophan and incorporates both atoms of a molecule of oxygen. Publication Abstract from PubMed Human indoleamine 2,3-dioxygenase (IDO) catalyzes the cleavage of the pyrrol ring of L-Trp and incorporates both atoms of a molecule of oxygen (O2). Here we report on the x-ray crystal structure of human IDO, complexed with the ligand inhibitor 4-phenylimidazole and cyanide. The overall structure of IDO shows two alpha-helical domains with the heme between them. A264 of the flexible loop in the heme distal side is in close proximity to the iron. A mutant analysis shows that none of the polar amino acid residues in the distal heme pocket are essential for activity, suggesting that, unlike the heme-containing monooxygenases (i.e., peroxidase and cytochrome P450), no protein group of IDO is essential in dioxygen activation or proton abstraction. These characteristics of the IDO structure provide support for a reaction mechanism involving the abstraction of a proton from the substrate by iron-bound dioxygen. Inactive mutants (F226A, F227A, and R231A) retain substrate-binding affinity, and an electron density map reveals that 2-(N-cyclohexylamino)ethane sulfonic acid is bound to these residues, mimicking the substrate. These findings suggest that strict shape complementarities between the indole ring of the substrate and the protein side chains are required, not for binding, but, rather, to permit the interaction between the substrate and iron-bound dioxygen in the first step of the reaction. This study provides the structural basis for a heme-containing dioxygenase mechanism, a missing piece in our understanding of heme chemistry. Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase.,Sugimoto H, Oda S, Otsuki T, Hino T, Yoshida T, Shiro Y Proc Natl Acad Sci U S A. 2006 Feb 21;103(8):2611-6. Epub 2006 Feb 13. PMID:16477023 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Dioxygenase 3D structures

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