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Visible light induc...
Visible light induction of an EPR split signal in photosystem II in the S2 state reveals the importance of charges in the oxygen evolving center during catalysis : a unifying model
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- Sjöholm, Johannes (author)
- Uppsala universitet,Molekylär biomimetik
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- Styring, Stenbjörn (author)
- Uppsala universitet,Molekylär biomimetik
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- Havelius, Kajsa G.V. (author)
- Uppsala universitet,Molekylär biomimetik
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- Ho, Felix M. (author)
- Uppsala universitet,Molekylär biomimetik
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(creator_code:org_t)
- 2012-02-29
- 2012
- English.
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In: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 51:10, s. 2054-2064
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- Cryogenic illumination of Photosystem II (PSII) can lead to the trapping of the metastable radical Y-z(center dot), the radical form of the redox-active tyrosine residue D1-Tyr161 (known as Y-z). Magnetic interaction between this radical and the CaMn4 cluster of PSII gives rise to so-called split electron paramagnetic resonance (EPR) signals with characteristics that are dependent on the S state. We report here the observation and characterization of a split EPR signal that can be directly induced from PSII centers in the S-2 state through visible light illumination at 10 K. We further show that the induction of this split signal takes place via a Mn-centered mechanism, in the same way as when using near-infrared light illumination [Koulougliotis, D., et al. (2003) Biochemistry 42, 3045-3053]. On the basis of interpretations of these results, and in combination with literature data for other split signals induced under a variety of conditions (temperature and light quality), we propose a unified model for the mechanisms of split signal induction across the four S states (S-0, S-1, S-2, and S-3). At the heart of this model is the stability or instability of the Y-z(center dot)(D1-His190)(+) pair that would be formed during cryogenic oxidation of Y-Z. Furthermore, the model is closely related to the sequence of transfers of protons and electrons from the CaMn4, cluster during the S cycle and further demonstrates the utility of the split signals in probing the immediate environment of the oxygen-evolving center in PSII.
Subject headings
- NATURVETENSKAP -- Biologi -- Biofysik (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biophysics (hsv//eng)
- NATURVETENSKAP -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)
Publication and Content Type
- ref (subject category)
- art (subject category)
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