2oyu
Indomethacin-(S)-alpha-ethyl-ethanolamide bound to Cyclooxygenase-1
Structural highlights
FunctionPGH1_SHEEP May play an important role in regulating or promoting cell proliferation in some normal and neoplastically transformed cells. 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 PubMedThe modification of the nonselective nonsteroidal anti-inflammatory drug, indomethacin, by amidation presents a promising strategy for designing novel cyclooxygenase (COX)-2-selective inhibitors. A series of alpha-substituted indomethacin ethanolamides, which exist as R/S-enantiomeric pairs, provides a means to study the impact of stereochemistry on COX inhibition. Comparative studies revealed that the R- and S-enantiomers of the alpha-substituted analogs inhibit COX-2 with almost equal efficacy, whereas COX-1 is selectively inhibited by the S-enantiomers. Mutagenesis studies have not been able to identify residues that manifest the enantioselectivity in COX-1. In an effort to understand the structural impact of chirality on COX-1 selectivity, the crystal structures of ovine COX-1 in complexes with an enantiomeric pair of these indomethacin ethanolamides were determined at resolutions between 2.75 and 2.85 A. These structures reveal unique, enantiomer-selective interactions within the COX-1 side pocket region that stabilize drug binding and account for the chiral selectivity observed with the (S)-alpha-substituted indomethacin ethanolamides. Kinetic analysis of binding demonstrates that both inhibitors bind quickly utilizing a two-step mechanism. However, the second binding step is readily reversible for the R-enantiomer, whereas for the S-enantiomer, it is not. These studies establish for the first time the structural and kinetic basis of high affinity binding of a neutral inhibitor to COX-1 and demonstrate that the side pocket of COX-1, previously thought to be sterically inaccessible, can serve as a binding pocket for inhibitor association. Structural basis of enantioselective inhibition of cyclooxygenase-1 by S-alpha-substituted indomethacin ethanolamides.,Harman CA, Turman MV, Kozak KR, Marnett LJ, Smith WL, Garavito RM J Biol Chem. 2007 Sep 21;282(38):28096-105. Epub 2007 Jul 26. PMID:17656360[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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