Subpicosecond equilibration of excitation energy in isolated photosystem II reaction centers.
Open Access
- 1 December 1992
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 89 (23) , 11632-11636
- https://doi.org/10.1073/pnas.89.23.11632
Abstract
Photosystem II reaction centers have been studied by femtosecond transient absorption spectroscopy. We demonstrate that it is possible to achieve good photoselectivity between the primary electron donor P680 and the majority of the accessory chlorins. Energy transfer can be observed in both directions between P680 and these accessory chlorins depending on which is initially excited. After excitation of either P680 or the other chlorins, the excitation energy is observed to equilibrate between the majority of these pigments at a rate of 100 +/- 50 fs-1. This energy-transfer equilibration takes place before any electron-transfer reactions and must therefore be taken into account in studies of primary electron-transfer reactions in photosystem II. We also show further evidence that the initially excited P680 excited singlet state is delocalized over at least two chlorins and that this delocalization lasts for at least 200 fs.Keywords
This publication has 13 references indexed in Scilit:
- Observation of pheophytin reduction in photosystem two reaction centers using femtosecond transient absorption spectroscopyBiochemistry, 1992
- Observation of multiple radical pair states in photosystem 2 reaction centersBiochemistry, 1991
- Epidemiology and Diagnosis of Acute Conjunctivitis at an Inner-city HospitalOphthalmology, 1989
- Kinetic and Energetic Model for the Primary Processes in Photosystem IIBiophysical Journal, 1988
- Picosecond kinetics of fluorescence and absorbance changes in photosystem II particles excited at low photon densityProceedings of the National Academy of Sciences, 1987
- Femtosecond spectroscopy of excitation energy transfer and initial charge separation in the reaction center of the photosynthetic bacterium Rhodopseudomonas viridisProceedings of the National Academy of Sciences, 1986
- Femtosecond spectroscopy of electron transfer in the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26: Direct electron transfer from the dimeric bacteriochlorophyll primary donor to the bacteriopheophytin acceptor with a time constant of 2.8 ± 0.2 psecProceedings of the National Academy of Sciences, 1986
- Picosecond kinetics of the initial photochemical electron-transfer reaction in bacterial photosynthetic reaction centersBiochemistry, 1985
- Reduction of pheophytin in the primary light reaction of photosystem IIFEBS Letters, 1977
- Light-induced changes of absorbance and electron spin resonance in small Photosystem II particlesBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1975