127969-05-5Relevant articles and documents
Structural basis of fatty acid substrate binding to cyclooxygenase-2
Vecchio, Alex J.,Simmons, Danielle M.,Malkowski, Michael G.
, p. 22152 - 22163 (2010)
The cyclooxygenases (COX-1 and COX-2) are membrane-associated heme-containing homodimers that generate prostaglandin H2 from arachidonic acid (AA). Although AA is the preferred substrate, other fatty acids are oxygenated by these enzymes with varying efficiencies. We determined the crystal structures of AA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) bound to Co3+-protoporphyrin IX-reconstituted murine COX-2 to 2.1, 2.4, and 2.65 A , respectively. AA, EPA, and docosahexaenoic acid bind in different conformations in each monomer constituting the homodimer in their respective structures such that one monomer exhibits nonproductive binding and the other productive binding of the substrate in the cyclooxygenase channel. The interactions identified between protein and substrate when bound to COX-1 are conserved in our COX-2 structures, with the only notable difference being the lack of interaction of the carboxylate of AA and EPA with the side chain of Arg-120. Leu-531 exhibits a different side chain conformation when the nonproductive and productive binding modes of AA are compared. Unlike COX-1, mutating this residue to Ala, Phe, Pro, or Thr did not result in a significant loss of activity or substrate binding affinity. Determination of the L531F:AA crystal structure resulted inAA binding in the same global conformation in each monomer. We speculate that the mobility of the Leu-531 side chain increases the volume available at the opening of the cyclooxygenase channel and contributes to the observed ability of COX-2 to oxygenate a broad spectrum of fatty acid and fatty ester substrates.
Human cyclooxygenase-2 is a sequence homodimer that functions as a conformational heterodimer
Dong, Liang,Vecchio, Alex J.,Sharma, Narayan P.,Jurban, Brice J.,Malkowski, Michael G.,Smith, William L.
experimental part, p. 19035 - 19046 (2012/03/26)
Prostaglandin endoperoxide H synthases 1 and 2, also known as cyclooxygenases (COXs) 1 and 2, convert arachidonic acid (AA) to prostaglandin endoperoxide H2. Prostaglandin endoperoxide H synthases are targets of nonspecific nonsteroidal anti-inflammatory drugs and COX-2-specific inhibitors called coxibs. PGHS-2 is a sequence homodimer. Each monomer has a peroxidase and a COX active site. We find that human PGHS-2 functions as a conformational heterodimer having a catalytic monomer (Ecat) and an allosteric monomer (Eallo). Heme binds tightly only to the peroxidase site of Ecat, whereas substrates, as well as certain inhibitors (e.g. celecoxib), bind the COX site of Ecat. Ecat is regulated by Eallo in a manner dependent on what ligand is bound to Eallo. Substrate and nonsubstrate fatty acids (FAs) and some COX inhibitors (e.g. naproxen) preferentially bind to the COX site of E allo. AA can bind to Ecat and Eallo, but the affinity of AA for Eallo is 25 times that for Ecat. Palmitic acid, an efficacious stimulator of human PGHS-2, binds only E allo in palmitic acid/murine PGHS-2 co-crystals. Nonsubstrate FAs can potentiate or attenuate actions of COX inhibitors depending on the FA and whether the inhibitor binds Ecat or Eallo. Our studies suggest that the concentration and composition of the free FA pool in the environment in which PGHS-2 functions in cells, the FA tone, is a key factor regulating PGHS-2 activity and its responses to COX inhibitors. We suggest that differences in FA tone occurring with different diets will likely affect both baseline prostanoid synthesis and responses to COX inhibitors.
COX-2-targeted imaging agents
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Page/Page column 6, (2008/06/13)
The presently disclosed subject matter provides a method for synthesizing a radiological imaging agent by reacting a COX-2-selective ligand with a compound comprising a detectable group, wherein the COX-2-selective ligand is a derivative of a non-steroidal anti-inflammatory drug (NSAID) comprising an ester moiety or a secondary amide moiety. Also provided are compositions that are synthesized using the method, as well as methods of using the compositions of the presently disclosed subject matter.
