1iw1

Crystal structure of a heme oxygenase (HmuO) from Corynebacterium diphtheriae complexed with heme in the ferrous state

Loading... Status: waiting for Mol* initialization Structural highlights 1iw1 is a 3 chain structure with sequence from Corynebacterium diphtheriae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM, SO4, SUC Related: 1iw0 Activity: Heme oxygenase, with EC number 1.14.99.3 Resources: FirstGlance, OCA, RCSB, PDBsum, TOPSAN Function [HMUO_CORDI] Allows the bacteria to use the host heme as an iron source. Involved in the oxidation of heme and subsequent release of iron from the heme moiety. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Crystal structures of the ferric and ferrous heme complexes of HmuO, a 24-kDa heme oxygenase of Corynebacterium diphtheriae, have been refined to 1.4 and 1.5 A resolution, respectively. The HmuO structures show that the heme group is closely sandwiched between the proximal and distal helices. The imidazole group of His-20 is the proximal heme ligand, which closely eclipses the beta- and delta-meso axis of the porphyrin ring. A long range hydrogen bonding network is present, connecting the iron-bound water ligand to the solvent water molecule. This enables proton transfer from the solvent to the catalytic site, where the oxygen activation occurs. In comparison to the ferric complex, the proximal and distal helices move closer to the heme plane in the ferrous complex. Together with the kinked distal helix, this movement leaves only the alpha-meso carbon atom accessible to the iron-bound dioxygen. The heme pocket architecture is responsible for stabilization of the ferric hydroperoxo-active intermediate by preventing premature heterolytic O-O bond cleavage. This allows the enzyme to oxygenate selectively at the alpha-meso carbon in HmuO catalysis. The crystal structures of the ferric and ferrous forms of the heme complex of HmuO, a heme oxygenase of Corynebacterium diphtheriae.,Hirotsu S, Chu GC, Unno M, Lee DS, Yoshida T, Park SY, Shiro Y, Ikeda-Saito M J Biol Chem. 2004 Mar 19;279(12):11937-47. Epub 2003 Nov 26. PMID:14645223 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Heme oxygenase

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