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PDBsum entry 1s8c
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Oxidoreductase
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PDB id
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1s8c
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Crystal structure of human heme oxygenase-1 in a complex with biliverdin.
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Authors
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L.Lad,
J.Friedman,
H.Li,
B.Bhaskar,
P.R.Ortiz de montellano,
T.L.Poulos.
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Ref.
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Biochemistry, 2004,
43,
3793-3801.
[DOI no: ]
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PubMed id
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Abstract
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Heme 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.
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