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Unequal misses duri...
Unequal misses during the flash-induced advancement of photosystem II : effects of the S state and acceptor side cycles
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- Pham, Long Vo (författare)
- Uppsala universitet,Molekylär biomimetik
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- Olmos, Julian David Janna (författare)
- Univ Warsaw, Ctr New Technol, Solar Fuels Lab, Banacha 2C, PL-02097 Warsaw, Poland;Jagiellonian Univ, Fac Biochem Biophys & Biotechnol, Dept Mol Biophys, Gronostajowa 7, PL-30387 Krakow, Poland
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- Chernev, Petko (författare)
- Uppsala universitet,Molekylär biomimetik
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- Kargul, Joanna (författare)
- Univ Warsaw, Ctr New Technol, Solar Fuels Lab, Banacha 2C, PL-02097 Warsaw, Poland
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- Messinger, Johannes (författare)
- Uppsala universitet,Umeå universitet,Kemiska institutionen,Department of Chemistry - Ångström, Uppsala University, Uppsala, Sweden,Molekylär biomimetik,Umea Univ, Chem Biol Ctr KBC, Dept Chem, Linnaeus Vag 6, S-90187 Umea, Sweden
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(creator_code:org_t)
- 2018-09-06
- 2019
- Engelska.
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Ingår i: Photosynthesis Research. - : Springer. - 0166-8595 .- 1573-5079. ; 139:1-3, s. 93-106
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Abstract
Ämnesord
Stäng
- Photosynthetic water oxidation is catalyzed by the oxygen-evolving complex (OEC) in photosystem II (PSII). This process is energetically driven by light-induced charge separation in the reaction center of PSII, which leads to a stepwise accumulation of oxidizing equivalents in the OEC (S-i states, i=0-4) resulting in O-2 evolution after each fourth flash, and to the reduction of plastoquinone to plastoquinol on the acceptor side of PSII. However, the S-i-state advancement is not perfect, which according to the Kok model is described by miss-hits (misses). These may be caused by redox equilibria or kinetic limitations on the donor (OEC) or the acceptor side. In this study, we investigate the effects of individual S state transitions and of the quinone acceptor side on the miss parameter by analyzing the flash-induced oxygen evolution patterns and the S-2, S-3 and S-0 state lifetimes in thylakoid samples of the extremophilic red alga Cyanidioschyzon merolae. The data are analyzed employing a global fit analysis and the results are compared to the data obtained previously for spinach thylakoids. These two organisms were selected, because the redox potential of Q(A)/Q(A)(-) in PSII is significantly less negative in C. merolae (E-m=-104mV) than in spinach (E-m=-163mV). This significant difference in redox potential was expected to allow the disentanglement of acceptor and donor side effects on the miss parameter. Our data indicate that, at slightly acidic and neutral pH values, the E-m of Q(A)(-)/Q(A) plays only a minor role for the miss parameter. By contrast, the increased energy gap for the backward electron transfer from Q(A)(-) to Pheo slows down the charge recombination reaction with the S-3 and S-2 states considerably. In addition, our data support the concept that the S-2 S-3 transition is the least efficient step during the oxidation of water to molecular oxygen in the Kok cycle of PSII.
Ämnesord
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Nyckelord
- Photosynthesis
- Photosystem II
- Mechanism of water oxidation
- Flash-induced oxygen oscillation pattern (FIOP)
- Unequal miss parameter
- Cyanidioschyzon merolae
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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