title: Pulsed Dipolar Spectroscopy Reveals That Tyrosyl Radicals Are Generated in Both Monomers of the Cyclooxygenase-2 Dimer.
abstract: Cyclooxygenases (COXs) are heme-containing sequence homodimers that utilize tyrosyl radical-based catalysis to oxygenate substrates. Tyrosyl radicals are formed from a single turnover of substrate in the peroxidase active site generating an oxy-ferryl porphyrin cation radical intermediate that subsequently gives rise to a Tyr-385 radical in the cyclooxygenase active site and a Tyr-504 radical nearby. We have utilized double-quantum coherence (DQC) spectroscopy to determine the distance distributions between Tyr-385 and Tyr-504 radicals in COX-2. The distances obtained with DQC confirm that Tyr-385 and Tyr-504 radicals were generated in each monomer and accurately match the distances measured in COX-2 crystal structures.
authors.affiliation: Department of Structural Biology, The State University of New York at Buffalo , Buffalo, New York 14203, United States.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Orlando
authors.affiliation: National Biomedical Center for Advanced Electron Spin Resonance Technology, Cornell University , Ithaca, New York 14853, United States.|Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Peter P
authors.initials: PP
authors.lastname: Borbat
authors.affiliation: National Biomedical Center for Advanced Electron Spin Resonance Technology, Cornell University , Ithaca, New York 14853, United States.|Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Elka R
authors.initials: ER
authors.lastname: Georgieva
authors.affiliation: National Biomedical Center for Advanced Electron Spin Resonance Technology, Cornell University , Ithaca, New York 14853, United States.|Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Jack H
authors.initials: JH
authors.lastname: Freed
authors.affiliation: Department of Structural Biology, The State University of New York at Buffalo , Buffalo, New York 14203, United States.|Hauptman-Woodward Medical Research Institute , Buffalo, New York 14203, United States.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Malkowski
mesh_terms: D051546:Cyclooxygenase 2 / Q000737:chemistry*; D019281:Dimerization; D008958:Models, Molecular; D013057:Spectrum Analysis / Q000379:methods*; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D014443:Tyrosine; D051546:Cyclooxygenase 2