Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria
Fast time-resolved EPR spectroscopy is used to study electron spin polarization (ESP) in perdeuterated native, Fe2+-containing reaction centers (RCs) of photosynthetic purple bacteria. The spin-correlated radical pair(SCRP) model (previously used to simulate ESP observed in Fe-depleted RCs (Höre, P....
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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1996
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| _version_ | 1797052472355717120 |
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| author | vandenBrink, J Hermolle, T Gast, P Hore, P Hoff, A |
| author_facet | vandenBrink, J Hermolle, T Gast, P Hore, P Hoff, A |
| author_sort | vandenBrink, J |
| collection | OXFORD |
| description | Fast time-resolved EPR spectroscopy is used to study electron spin polarization (ESP) in perdeuterated native, Fe2+-containing reaction centers (RCs) of photosynthetic purple bacteria. The spin-correlated radical pair(SCRP) model (previously used to simulate ESP observed in Fe-depleted RCs (Höre, P. J.; Hunter, D. A.; McKie, C. D.; Hoff, A. J. Chem. Phys. Lett. 1987, 737, 495) is extended to include the large anisotropy arising from the magnetic interactions between Fe2+ and the reduced primary electron-acceptor quinone (QA'~), which results in different quantization axes for the P+ and the (QA~Fe2+) spins. Using spectral simulations, it is shown that the ESP spectrum is solely due to the P+ part of the spin-correlated radical pair [P+(QA~Fe2+)], whereas the rapid decay of the spin-polarized signal is due to spin-lattice relaxation of the (QA~Fe2+) complex. The simulations are very sensitive to the relative orientation of the g matrices of P+ and (QA'~Fe2+). Using orientation II of the g matrix of the oxidized primary donor P+ (Klette, R.; Törring, J. T.; Plato, M.; Möbius, K.; Bönigk, B.; Lubitz, W. J. Phys. Chem. 1993, 97, 2015), the orientation of the g matrix of (QA~Fe2+) is assessed. Finally, it is shown that the ESP spectrum of perdeuterated native, Fe2+containing RCs of Rhodopseudomonas (Rps.) 'viridis is virtually identical to the spectrum obtained for perdeuterated native Rhodobacter (Rb.) sphaeroides, showing an AEA pattern (A denotes absorption and E emission). This result indicates that the magnetic axes of P+ and (QA'"Fe2+) have (nearly) the same directions relative to one another in both species. © 1996 American Chemical Society and Notes. |
| first_indexed | 2024-03-06T18:32:03Z |
| format | Journal article |
| id | oxford-uuid:09fb97a2-c184-42ed-9efb-5a060d8187df |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T18:32:03Z |
| publishDate | 1996 |
| record_format | dspace |
| spelling | oxford-uuid:09fb97a2-c184-42ed-9efb-5a060d8187df2022-03-26T09:21:20ZElectron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteriaJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:09fb97a2-c184-42ed-9efb-5a060d8187dfEnglishSymplectic Elements at Oxford1996vandenBrink, JHermolle, TGast, PHore, PHoff, AFast time-resolved EPR spectroscopy is used to study electron spin polarization (ESP) in perdeuterated native, Fe2+-containing reaction centers (RCs) of photosynthetic purple bacteria. The spin-correlated radical pair(SCRP) model (previously used to simulate ESP observed in Fe-depleted RCs (Höre, P. J.; Hunter, D. A.; McKie, C. D.; Hoff, A. J. Chem. Phys. Lett. 1987, 737, 495) is extended to include the large anisotropy arising from the magnetic interactions between Fe2+ and the reduced primary electron-acceptor quinone (QA'~), which results in different quantization axes for the P+ and the (QA~Fe2+) spins. Using spectral simulations, it is shown that the ESP spectrum is solely due to the P+ part of the spin-correlated radical pair [P+(QA~Fe2+)], whereas the rapid decay of the spin-polarized signal is due to spin-lattice relaxation of the (QA~Fe2+) complex. The simulations are very sensitive to the relative orientation of the g matrices of P+ and (QA'~Fe2+). Using orientation II of the g matrix of the oxidized primary donor P+ (Klette, R.; Törring, J. T.; Plato, M.; Möbius, K.; Bönigk, B.; Lubitz, W. J. Phys. Chem. 1993, 97, 2015), the orientation of the g matrix of (QA~Fe2+) is assessed. Finally, it is shown that the ESP spectrum of perdeuterated native, Fe2+containing RCs of Rhodopseudomonas (Rps.) 'viridis is virtually identical to the spectrum obtained for perdeuterated native Rhodobacter (Rb.) sphaeroides, showing an AEA pattern (A denotes absorption and E emission). This result indicates that the magnetic axes of P+ and (QA'"Fe2+) have (nearly) the same directions relative to one another in both species. © 1996 American Chemical Society and Notes. |
| spellingShingle | vandenBrink, J Hermolle, T Gast, P Hore, P Hoff, A Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
| title | Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
| title_full | Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
| title_fullStr | Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
| title_full_unstemmed | Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
| title_short | Electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
| title_sort | electron spin polarization of the oxidized primary electron donor in reaction centers of photosynthetic purple bacteria |
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