Abstract
Replacement of methionine, the natural axial ligand to the primary electron acceptor (A0) in Photosystem I, with a series of different amino acids results in dramatic increase of the A0 − lifetime from ̃20 ps in wild type to a few nanoseconds in the mutants in the case of Chlamydomonas reinhardtii (Ramesh et al. 2004, 2007). This effect is similar independently if the mutation affects A-side or B-side A0. This observation confirms an existence of two equivalent primary electron acceptors in both symmetric branches of Photosystem I in Chlamydomonas reinhardtii, which makes this photosystem unusual among other photosystems (from purple bacteria, PS II), which are essentially unidirectional. However, it is still not clear if the bidirectionality of electron transfer in Photosystem I is complete, i.e. if the electron from A0 − reaches A1 in both branches or takes another route in the “non-active” branch. In order to solve this issue, in this contribution we attempted to compare kinetics of A0 − reoxidation to the kinetics of A1 − formation in the case of B-side A0 mutant with methionine replaced by serine.
Keywords
- Photosystem I
- electron transfer
- primary electron acceptor A0
- mutants
- femtosecond transient absorption
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References
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Giera, W. et al. (2008). A0 → A1 Electron Transfer in Chlamydomonas reinhardtii PS I with Replaced A0 Axial Ligand. In: Allen, J.F., Gantt, E., Golbeck, J.H., Osmond, B. (eds) Photosynthesis. Energy from the Sun. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-6709-9_15
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DOI: https://doi.org/10.1007/978-1-4020-6709-9_15
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-4020-6707-5
Online ISBN: 978-1-4020-6709-9
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