The S 1 to S 2 and S 2 to S 3 state transitions in plant photosystem II: relevance to the functional and structural heterogeneity of the water oxidizing complex.

Autor: Pavlou A; Molecular Biomimetics, Department of Chemistry-Ångström, Uppsala University, P.O. Box 523, 751 20, Uppsala, Sweden., Styring S; Molecular Biomimetics, Department of Chemistry-Ångström, Uppsala University, P.O. Box 523, 751 20, Uppsala, Sweden., Mamedov F; Molecular Biomimetics, Department of Chemistry-Ångström, Uppsala University, P.O. Box 523, 751 20, Uppsala, Sweden. fikret.mamedov@kemi.uu.se.
Jazyk: angličtina
Zdroj: Photosynthesis research [Photosynth Res] 2024 Dec; Vol. 162 (2-3), pp. 401-411. Date of Electronic Publication: 2024 Apr 25.
DOI: 10.1007/s11120-024-01096-4
Abstrakt: In Photosystem II, light-induced water splitting occurs via the S state cycle of the CaMn 4 O 5 -cluster. To understand the role of various possible conformations of the CaMn 4 O 5 -cluster in this process, the temperature dependence of the S 1  → S 2 and S 2  → S 3 state transitions, induced by saturating laser flashes, was studied in spinach photosystem II membrane preparations under different conditions. The S 1  → S 2 transition temperature dependence was shown to be much dependent on the type of the cryoprotectant and presence of 3.5% methanol, resulting in the variation of transition half-inhibition temperature by 50 K. No similar effect was observed for the S 2  → S 3 state transition, for which we also show that both the low spin g = 2.0 multiline and high spin g = 4.1 EPR configurations of the S 2 state advance with similar efficiency to the S 3 state, both showing a transition half-inhibition temperature of 240 K. This was further confirmed by following the appearance of the Split S 3 EPR signal. The results are discussed in relevance to the functional and structural heterogeneity of the water oxidizing complex intermediates in photosystem II.
Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests.
(© 2024. The Author(s).)
Databáze: MEDLINE
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