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PDBsum entry 3olt
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Oxidoreductase
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PDB id
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3olt
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References listed in PDB file
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Key reference
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Title
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The structural basis of endocannabinoid oxygenation by cyclooxygenase-2.
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Authors
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A.J.Vecchio,
M.G.Malkowski.
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Ref.
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J Biol Chem, 2011,
286,
20736-20745.
[DOI no: ]
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PubMed id
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Abstract
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The cyclooxygenases (COX-1 and COX-2) oxygenate arachidonic acid (AA) in the
committed step of prostaglandin biogenesis. Substitutions of I434V, H513R, and
I523V constitute the only differences in residues lining the cyclooxygenase
channel between COX-1 and COX-2. These changes create a hydrophobic pocket in
COX-2, with Arg-513 located at the base of the pocket, which has been exploited
in the design of COX-2-selective inhibitors. Previous studies have shown that
COX-2, but not COX-1, can oxygenate endocannabinoid substrates, including
2-arachidonoyl glycerol (2-AG). To investigate the isoform-specific structural
basis of endocannabinoid binding to COX-2, we determined the crystal structure
of the 2-AG isomer 1-arachidonoyl glycerol (1-AG) in complex with wild type and
R513H murine (mu) COX-2 to 2.2 and 2.35 Å, respectively, and R513H muCOX-2 in
complex with AA to 2.45 Å resolution. The 2,3-dihydroxypropyl moiety of 1-AG
binds near the opening of the cyclooxygenase channel in the space vacated by the
movement of the Leu-531 side chain, validating our previous hypothesis
implicating the flexibility of the Leu-531 side chain as a determinant for the
ability of COX-2 to oxygenate endocannabinoid substrates. Functional analyses
carried out to compliment our structural findings indicated that Y355F and R513H
muCOX-2 constructs had no effect on the oxygenation of 1-AG and 2-AG, whereas
substitutions that resulted in a shortened side chain for Leu-531 had only
modest effects. Both AA and 1-AG bind to R513H muCOX-2 in conformations similar
to those observed in the co-crystal structures of these substrates with wild
type enzyme.
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