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PDBsum entry 5fdq
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Oxidoreductase/inhibitor
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PDB id
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5fdq
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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 aspirin-Acetylated human cyclooxygenase-2: insight into the formation of products with reversed stereochemistry.
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Authors
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M.J.Lucido,
B.J.Orlando,
A.J.Vecchio,
M.G.Malkowski.
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Ref.
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Biochemistry, 2016,
55,
1226-1238.
[DOI no: ]
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PubMed id
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Abstract
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Aspirin and other nonsteroidal anti-inflammatory drugs target the cyclooxygenase
enzymes (COX-1 and COX-2) to block the formation of prostaglandins. Aspirin is
unique in that it covalently modifies each enzyme by acetylating Ser-530 within
the cyclooxygenase active site. Acetylation of COX-1 leads to complete loss of
activity, while acetylation of COX-2 results in the generation of the
monooxygenated product 15(R)-hydroxyeicosatetraenoic acid (15R-HETE). Ser-530
has also been shown to influence the stereochemistry for the addition of oxygen
to the prostaglandin product. We determined the crystal structures of S530T
murine (mu) COX-2, aspirin-acetylated human (hu) COX-2, and huCOX-2 in complex
with salicylate to 1.9, 2.0, and 2.4 Å, respectively. The structures reveal
that (1) the acetylated Ser-530 completely blocks access to the hydrophobic
groove, (2) the observed binding pose of salicylate is reflective of the
enzyme-inhibitor complex prior to acetylation, and (3) the observed Thr-530
rotamer in the S530T muCOX-2 crystal structure does not impede access to the
hydrophobic groove. On the basis of these structural observations, along with
functional analysis of the S530T/G533V double mutant, we propose a working
hypothesis for the generation of 15R-HETE by aspirin-acetylated COX-2. We also
observe differential acetylation of COX-2 purified in various detergent systems
and nanodiscs, indicating that detergent and lipid binding within the
membrane-binding domain of the enzyme alters the rate of the acetylation
reaction in vitro.
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