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EPR characterization of photosystem II from different domains of the thylakoid membrane
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
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2008 (English)In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 47, no 12, 3883-3891 p.Article in journal (Refereed) Published
Abstract [en]

We report electron paramagnetic resonance (EPR) studies on photosystem, 11 (PSII) from higher plants in five different domains of the thylakoid membrane prepared by sonication and two-phase partitioning. The domains studied were the grana core, the entire grana stack, the grana margins, the stroma lamellae and the purified stromal fraction, Y100. The electron transport properties of both donor and acceptor sides of PSII such as oxygen evolution, cofactors Y-D, Q(A), the CaMn4-cluster, and Cytb559 were investigated. The PSII content was estimated on the basis of oxidized YD and Q(A)(_) Fe2+ signal from the acceptor side vs Chl content (100% in the grana core fraction). It was found to be about 82% in the grana, 59% in the margins, 35% in the stroma and 15% in the Y100 fraction. The most active PSH centers were found in the granal fractions as was estimated from the rates of electron transfer and the S-2 State multiline EPR signal. In the margin and stromal fractions the multiline signal was smaller (40 and 33%, respectively). The S2 state multiline could not be induced in the Y100 fraction. In addition, the oxidized LP Cytb559 prevailed in the stromal fractions while the HP form dominated in the grana core. The margins and entire grana fractions have Cytb559 in both potential forms. These data together with previous analyses indicate that the sequence of activation of the PSII properties can be represented as: PSII content > oxygen evolution > reduced Cytb559 > dimerization of PSII centers in all fractions of the thylakoid membrane with the gradual increase from stromal fractions via margin to the grana core fraction. The results further support the existence of a PSII activity gradient which reflects lateral movement and photoactivation of PSII centers in the thylakoid membrane. The possible role of the PSII redox components in this process is discussed.

Place, publisher, year, edition, pages
2008. Vol. 47, no 12, 3883-3891 p.
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-110479DOI: 10.1021/bi701913kISI: 000254127900031OAI: oai:DiVA.org:uu-110479DiVA: diva2:277213
Available from: 2009-11-16 Created: 2009-11-16 Last updated: 2016-04-22Bibliographically approved

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Mamedov, FikretStyring, Stenbjörn
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