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Proton Equilibria in the Manganese Cluster of Photosystem II Control the Intensities of the S0 and S2 State g ~ 2 Electron Paramagnetic Resonance Signals

Geijer, Paulina LU ; Deák, Zsuzsanna and Styring, Stenbjörn LU (2000) In Biochemistry 39(23). p.6763-6772
Abstract
We have studied the pH effect on the S0 and S2 multiline electron paramagnetic resonance (EPR) signals from the water-oxidizing complex of photosystem II. Around pH 6, the maximum signal intensities were detected. On both the acidic and alkaline sides of pH 6, the intensities of the EPR signals decreased. Two pKs were determined for the S0 multiline signal; pK1 = 4.2 ± 0.2 and pK2 = 8.0 ± 0.1, and for the S2 multiline signal the pKs were pK1 = 4.5 ± 0.1 and pK2 = 7.6 ± 0.1. The intensity of the S0-state EPR signal was partly restored when the pH was changed from acidic or alkaline pH back to pH ~ 6. In the S2 state we observed partial recovery of the multiline signal when going from alkaline pH back to pH 6, whereas no significant recovery... (More)
We have studied the pH effect on the S0 and S2 multiline electron paramagnetic resonance (EPR) signals from the water-oxidizing complex of photosystem II. Around pH 6, the maximum signal intensities were detected. On both the acidic and alkaline sides of pH 6, the intensities of the EPR signals decreased. Two pKs were determined for the S0 multiline signal; pK1 = 4.2 ± 0.2 and pK2 = 8.0 ± 0.1, and for the S2 multiline signal the pKs were pK1 = 4.5 ± 0.1 and pK2 = 7.6 ± 0.1. The intensity of the S0-state EPR signal was partly restored when the pH was changed from acidic or alkaline pH back to pH ~ 6. In the S2 state we observed partial recovery of the multiline signal when going from alkaline pH back to pH 6, whereas no significant recovery of the S2 multiline signal was observed when the pH was changed from acidic pH back to pH 6. Several possible explanations for the intensity changes as a function of pH are discussed. Some are ruled out, such as disintegration of the Mn cluster or decay of the S states and formal Cl- and Ca2+ depletion. The altered EPR signal intensities probably reflect the protonation/deprotonation of ligands to the Mn cluster or the oxo bridges between the Mn ions. Also, the possibility of decreased multiline signal intensities at alkaline pH as an effect of changed redox potential of YZ is put forward. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
39
issue
23
pages
6763 - 6772
publisher
The American Chemical Society
external identifiers
  • scopus:0039596979
ISSN
0006-2960
DOI
10.1021/bi992878c
language
English
LU publication?
yes
id
1de90f03-7772-4660-b71c-1e7a73827b18 (old id 125099)
date added to LUP
2007-07-04 16:54:59
date last changed
2017-04-09 03:37:07
@article{1de90f03-7772-4660-b71c-1e7a73827b18,
  abstract     = {We have studied the pH effect on the S0 and S2 multiline electron paramagnetic resonance (EPR) signals from the water-oxidizing complex of photosystem II. Around pH 6, the maximum signal intensities were detected. On both the acidic and alkaline sides of pH 6, the intensities of the EPR signals decreased. Two pKs were determined for the S0 multiline signal; pK1 = 4.2 ± 0.2 and pK2 = 8.0 ± 0.1, and for the S2 multiline signal the pKs were pK1 = 4.5 ± 0.1 and pK2 = 7.6 ± 0.1. The intensity of the S0-state EPR signal was partly restored when the pH was changed from acidic or alkaline pH back to pH ~ 6. In the S2 state we observed partial recovery of the multiline signal when going from alkaline pH back to pH 6, whereas no significant recovery of the S2 multiline signal was observed when the pH was changed from acidic pH back to pH 6. Several possible explanations for the intensity changes as a function of pH are discussed. Some are ruled out, such as disintegration of the Mn cluster or decay of the S states and formal Cl- and Ca2+ depletion. The altered EPR signal intensities probably reflect the protonation/deprotonation of ligands to the Mn cluster or the oxo bridges between the Mn ions. Also, the possibility of decreased multiline signal intensities at alkaline pH as an effect of changed redox potential of YZ is put forward.},
  author       = {Geijer, Paulina and Deák, Zsuzsanna and Styring, Stenbjörn},
  issn         = {0006-2960},
  language     = {eng},
  number       = {23},
  pages        = {6763--6772},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {Proton Equilibria in the Manganese Cluster of Photosystem II Control the Intensities of the S0 and S2 State g ~ 2 Electron Paramagnetic Resonance Signals},
  url          = {http://dx.doi.org/10.1021/bi992878c},
  volume       = {39},
  year         = {2000},
}