Characterization of the water oxidizing complex of photosystem II of the Chl d-containing cyanobacterium Acaryochloris marina via its reactivity towards endogenous electron donors and acceptors
| Autor: | Johannes Messinger, H.-J. Eckert, Birgit Nöring, Gernot Renger, Dmitriy Shevela |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Chlorophyll
Models Molecular Photosynthetic reaction centre Light Photosystem II Acaryochloris marina Chlorophyll d General Physics and Astronomy Cyanobacteria Photochemistry Models Biological Electron Transport chemistry.chemical_compound Computer Simulation Physical and Theoretical Chemistry biology Oxygen evolution Photosystem II Protein Complex Water food and beverages P680 biology.organism_classification Oxygen Models Chemical chemistry Thylakoid Spinach Oxidation-Reduction |
| Zdroj: | Phys. Chem. Chem. Phys.. 8:3460-3466 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/b604389e |
| Popis: | Acaroychloris (A.) marina is a unique oxygen evolving organism that contains a large amount of chlorophyll d (Chl d) and only very few Chl a molecules. This feature raises questions on the nature of the photoactive pigment, which supports light-induced oxidative water splitting in Photosystem II (PS II). In this study, flash-induced oxygen evolution patterns (FIOPs) were measured to address the question whether the S(i) state transition probabilities and/or the redox-potentials of the water oxidizing complex (WOC) in its different S(i) states are altered in A. marina cells compared to that of spinach thylakoids. The analysis of the obtained data within the framework of different versions of the Kok model reveals that in light activated A. marina cells the miss probability is similar compared to spinach thylakoids. This finding indicates that the redox-potentials and kinetics within the WOC, of the reaction center (P680) and of Y(Z) are virtually the same for both organisms. This conclusion is strongly supported by lifetime measurements of the S(2) and S(3) states. Virtually identical time constants were obtained for the slow phase of deactivation. Kinetic differences in the fast phase of S(2) and S(3) decay between A. marina cells and spinach thylakoids reflect a shift of the E(m) of Y(D)/Y(D)(ox) to lower values in the former compared to the latter organisms, as revealed by the observation of an opposite change in the kinetics of S(0) oxidation to S(1) by Y(D)(ox). A slightly increased double hit probability in A. marina cells is indicative of a faster Q(A)(-) to Q(B) electron transfer in these cells compared to spinach thylakoids. |
| Databáze: | OpenAIRE |
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