The accessory bacteriochlorophyll: a real electron carrier in primary photosynthesis.
Open Access
- 15 December 1993
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 90 (24), 11757-11761
- https://doi.org/10.1073/pnas.90.24.11757
Abstract
The primary electron transfer in reaction centers of Rhodobacter sphaeroides is studied by subpicosecond absorption spectroscopy with polarized light in the spectral range of 920-1040 nm. Here the bacteriochlorophyll anion radical has an absorption band while the other pigments of the reaction center have vanishing ground-state absorption. The transient absorption data exhibit a pronounced 0.9-ps kinetic component which shows a strong dichroism. Evaluation of the data yields an angle between the transition moments of the special pair and the species related with the 0.9-ps kinetic component of 26 +/- 8 degrees. This angle compares favorably with the value of 29 degrees expected for the reduced accessory bacteriochlorophyll. Extensive transient absorbance data are fully consistent with a stepwise electron transfer via the accessory bacteriochlorophyll.Keywords
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