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Methanol modification of the electron paramagnetic resonance signals from the S0 and S2 states of the water-oxidizing complex of Photosystem II

Deák, Zsuzsanna; Peterson Årsköld, Sindra LU ; Geijer, Paulina LU ; Åhrling, Karin A and Styring, Stenbjörn LU (1999) In Biochimica et Biophysica Acta - Bioenergetics 1412(3). p.240-249
Abstract
The Mn-derived electron paramagnetic resonance (EPR) multiline signal from the S0 state of the water-oxidizing complex is observable only in the presence methanol. In the present study, we have characterized the effect of methanol on the EPR signals from the S0 and S2 states as well as on the EPR Signal IIslow originating from the TyrosineDox radical. The amplitudes of the S0 and S2 multiline signals increase with the methanol concentration in a similar way, whereas the S2 g=4.1 excited state signal amplitude shows a concomitant decrease. The methanol concentration at which half of the spectral change has occurred is ~0.2% and the effect is saturating around 5%. Methanol has an effect on the microwave power saturation of the S2 multiline... (More)
The Mn-derived electron paramagnetic resonance (EPR) multiline signal from the S0 state of the water-oxidizing complex is observable only in the presence methanol. In the present study, we have characterized the effect of methanol on the EPR signals from the S0 and S2 states as well as on the EPR Signal IIslow originating from the TyrosineDox radical. The amplitudes of the S0 and S2 multiline signals increase with the methanol concentration in a similar way, whereas the S2 g=4.1 excited state signal amplitude shows a concomitant decrease. The methanol concentration at which half of the spectral change has occurred is ~0.2% and the effect is saturating around 5%. Methanol has an effect on the microwave power saturation of the S2 multiline signal, as well. The microwave power at half saturation (P1/2) is 85 mW in the presence of methanol, whereas the signal relaxes much slower (P1/2~27 mW) without. The relaxation of Signal IIslow in the presence of methanol has also been investigated. The P1/2 value of Signal IIslow oscillates with the S cycle in a similar way as without methanol, but the P1/2 values are consistently lower in the methanol-containing samples. From the results, we conclude that methanol modifies the magnetic properties of the S0 and S2 states in a similar way. The possible site and nature of methanol binding is discussed. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Electron paramagnetic resonance, Photosystem II, Methanol, Manganese cluster
in
Biochimica et Biophysica Acta - Bioenergetics
volume
1412
issue
3
pages
240 - 249
publisher
Elsevier
external identifiers
  • scopus:0039090692
ISSN
0005-2728
DOI
10.1016/S0005-2728(99)00064-X
language
English
LU publication?
yes
id
4da1b1be-e726-43e2-8bd6-5295572ee61a (old id 125276)
date added to LUP
2007-07-04 16:10:12
date last changed
2017-10-29 04:15:39
@article{4da1b1be-e726-43e2-8bd6-5295572ee61a,
  abstract     = {The Mn-derived electron paramagnetic resonance (EPR) multiline signal from the S0 state of the water-oxidizing complex is observable only in the presence methanol. In the present study, we have characterized the effect of methanol on the EPR signals from the S0 and S2 states as well as on the EPR Signal IIslow originating from the TyrosineDox radical. The amplitudes of the S0 and S2 multiline signals increase with the methanol concentration in a similar way, whereas the S2 g=4.1 excited state signal amplitude shows a concomitant decrease. The methanol concentration at which half of the spectral change has occurred is ~0.2% and the effect is saturating around 5%. Methanol has an effect on the microwave power saturation of the S2 multiline signal, as well. The microwave power at half saturation (P1/2) is 85 mW in the presence of methanol, whereas the signal relaxes much slower (P1/2~27 mW) without. The relaxation of Signal IIslow in the presence of methanol has also been investigated. The P1/2 value of Signal IIslow oscillates with the S cycle in a similar way as without methanol, but the P1/2 values are consistently lower in the methanol-containing samples. From the results, we conclude that methanol modifies the magnetic properties of the S0 and S2 states in a similar way. The possible site and nature of methanol binding is discussed.},
  author       = {Deák, Zsuzsanna and Peterson Årsköld, Sindra and Geijer, Paulina and Åhrling, Karin A and Styring, Stenbjörn},
  issn         = {0005-2728},
  keyword      = {Electron paramagnetic resonance,Photosystem II,Methanol,Manganese cluster},
  language     = {eng},
  number       = {3},
  pages        = {240--249},
  publisher    = {Elsevier},
  series       = {Biochimica et Biophysica Acta - Bioenergetics},
  title        = {Methanol modification of the electron paramagnetic resonance signals from the S0 and S2 states of the water-oxidizing complex of Photosystem II},
  url          = {http://dx.doi.org/10.1016/S0005-2728(99)00064-X},
  volume       = {1412},
  year         = {1999},
}