title: Binding of ibuprofen, ketorolac, and diclofenac to COX-1 and COX-2 studied by saturation transfer difference NMR.
abstract: Saturation transfer difference NMR (STD-NMR) spectroscopy has emerged as a powerful screening tool and a straightforward way to study the binding epitopes of active compounds in early stage lead discovery in pharmaceutical research. Here we report the application of STD-NMR to characterize the binding of the anti-inflammatory drugs ibuprofen, diclofenac, and ketorolac to COX-1 and COX-2. Using well-studied COX inhibitors and by comparing STD signals with crystallographic structures, we show that there is a relation between the orientations of ibuprofen and diclofenac in the COX-2 active site and the relative STD responses detected in the NMR experiments. On the basis of this analysis, we propose that ketorolac should bind to the COX-2 active site in an orientation similar to that of diclofenac. We also show that the combination of STD-NMR with competition experiments constitutes a valuable tool to address the recently proposed behavior of COX-2 as functional heterodimers and complements enzyme activity studies in the effort to rationalize COX inhibition mechanisms.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia-UNL, REQUIMTE, CQFB, 2829-516 Caparica, Portugal.
authors.forename: Aldino
authors.initials: A
authors.lastname: Viegas
authors.forename: João
authors.initials: J
authors.lastname: Manso
authors.forename: Marta C
authors.initials: MC
authors.lastname: Corvo
authors.forename: M Manuel B
authors.initials: MM
authors.lastname: Marques
authors.forename: Eurico J
authors.initials: EJ
authors.lastname: Cabrita
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D020134:Catalytic Domain; D051545:Cyclooxygenase 1 / Q000737:chemistry*; D051546:Cyclooxygenase 2 / Q000737:chemistry*; D016861:Cyclooxygenase Inhibitors / Q000737:chemistry*; D004008:Diclofenac / Q000737:chemistry*; D005260:Female; D007052:Ibuprofen / Q000737:chemistry*; D020910:Ketorolac / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D012756:Sheep
chemical_list: D016861:Cyclooxygenase Inhibitors; D004008:Diclofenac; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D007052:Ibuprofen; D020910:Ketorolac