1ulx

Partially photolyzed structure of CO-bound heme-heme oxygenase complex

spinqualitylabelsall models 1ulx, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ulx is a 1 chain structure with sequence from Buffalo rat. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CMO, HEM Related: 1ix4, 1vgi Activity: Heme oxygenase, with EC number 1.14.99.3 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [HMOX1_RAT] Heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. Under physiological conditions, the activity of heme oxygenase is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed. 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 Heme oxygenase (HO) catalyzes physiological heme degradation using O(2) and reducing equivalents to produce biliverdin, iron, and CO. Notably, the HO reaction proceeds without product inhibition by CO, which is generated in the conversion reaction of alpha-hydroxyheme to verdoheme, although CO is known to be a potent inhibitor of HO and other heme proteins. In order to probe how endogenous CO is released from the reaction site, we collected X-ray diffraction data from a crystal of the CO-bound form of the ferrous heme-HO complex in the dark and under illumination by a red laser at approximately 35 K. The difference Fourier map indicates that the CO ligand is partially photodissociated from the heme and that the photolyzed CO is trapped in a hydrophobic cavity adjacent to the heme pocket. This hydrophobic cavity was occupied also by xenon, which is similar to CO in terms of size and properties. Taking account of the affinity of CO for the ferrous verdoheme-HO complex being much weaker than that for the ferrous heme complex, the CO derived from alpha-hydroxyheme would be trapped preferentially in the hydrophobic cavity but not coordinated to the iron of verdoheme. This structural device would ensure the smooth progression of the subsequent reaction, from verdoheme to biliverdin, which requires O(2) binding to verdoheme. CO-trapping site in heme oxygenase revealed by photolysis of its co-bound heme complex: mechanism of escaping from product inhibition.,Sugishima M, Sakamoto H, Noguchi M, Fukuyama K J Mol Biol. 2004 Jul 30;341(1):7-13. PMID:15312758 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Heme oxygenase 3D structures

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