1s8c
From Proteopedia
Crystal structure of human heme oxygenase in a complex with biliverdine
Structural highlights
Disease[HMOX1_HUMAN] Defects in HMOX1 are the cause of heme oxygenase 1 deficiency (HMOX1D) [MIM:614034]. A disease characterized by impaired stress hematopoiesis, resulting in marked erythrocyte fragmentation and intravascular hemolysis, coagulation abnormalities, endothelial damage, and iron deposition in renal and hepatic tissues. Clinical features include persistent hemolytic anemia, asplenia, nephritis, generalized erythematous rash, growth retardation and hepatomegaly.[1] Function[HMOX1_HUMAN] 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 PubMedHeme oxygenase oxidatively cleaves heme to biliverdin, leading to the release of iron and CO through a process in which the heme participates both as a cofactor and as a substrate. Here we report the crystal structure of the product, iron-free biliverdin, in a complex with human HO-1 at 2.19 A. Structural comparisons of the human biliverdin-HO-1 structure with its heme complex and the recently published rat HO-1 structure in a complex with the biliverdin-iron chelate [Sugishima, M., Sakamoto, H., Higashimoto, Y., Noguchi, M., and Fukuyama, K. (2003) J. Biol. Chem. 278, 32352-32358] show two major differences. First, in the absence of an Fe-His bond and solvent structure in the active site, the distal and proximal helices relax and adopt an "open" conformation which most likely encourages biliverdin release. Second, iron-free biliverdin occupies a different position and orientation relative to heme and the biliverdin-iron complex. Biliverdin adopts a more linear conformation and moves from the heme site to an internal cavity. These structural results provide insight into the rate-limiting step in HO-1 catalysis, which is product, biliverdin, release. Crystal structure of human heme oxygenase-1 in a complex with biliverdin.,Lad L, Friedman J, Li H, Bhaskar B, Ortiz de Montellano PR, Poulos TL Biochemistry. 2004 Apr 6;43(13):3793-801. PMID:15049686[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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