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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.

SUBMITTER: Orlando BJ

PROVIDER: S-EPMC4707933 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Pulsed Dipolar Spectroscopy Reveals That Tyrosyl Radicals Are Generated in Both Monomers of the Cyclooxygenase-2 Dimer.

Orlando Benjamin J BJ Borbat Peter P PP Georgieva Elka R ER Freed Jack H JH Malkowski Michael G MG

Biochemistry 20151207 50

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 distribut ...[more]

PMID: 26636181

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