Publication: Kinetic simulations of chlorophyll and carotenoid cation radical dynamics in photosystem II .
All || By Area || By Year| Title | Kinetic simulations of chlorophyll and carotenoid cation radical dynamics in photosystem II . | Authors/Editors* | Serguei Vassiliev1, Doug Bruce1 and Gary Brudvig2 |
|---|---|
| Where published* | Biophys. J. |
| How published* | Journal |
| Year* | 2007 |
| Volume | -1 |
| Number | -1 |
| Pages | |
| Publisher | |
| Keywords | |
| Link | |
| Abstract |
When electron-donation from the water-oxidizing complex in PSII is inhibited, chlorophyll (Chl), beta-carotene (Car) and cytochrome b559 serve as alternative electron donors in a proposed photoprotection mechanism. We simulated the dynamics of cation radicals in PSII to analyze possible pathways of cation radical formation. Simulations were based on pairwise rates of cation radical transfer between cofactors calculated using the âDutton rulerâ from the recent X-ray crystal structure of PSII (2AXT.pdb) and the published set of Chl and Car redox potentials (Ishikita et al., 2005). We aimed to reproduce with our simulations the following experimental data: 0.9 ms P+QA- recombination time, 5% single flash cation radical yield, cation radical quenching by reduced cytochrome b559 and the formation of one Chl and two Car cation radicals. We analyzed two possible pathways of cation radical formation: one involving chlorophyll ChlZ/D1 and the other involving chlorophyll ChlZ/D2. Results of our simulations show that only the pathway of cation radical formation: P680+ â Pheo/D1 â Car101/D1 â ChlZ/D1 â Chl41/CP43 â Chls/CP43 â [Chl47, Car111, Car112]/CP43 is consistent with the target data. This result provides new insight into the alternate electron-donation pathways to P680+. |
Back to page 69 of list