Relaxation behaviour of the tyrosine Y-D radical in photosystem II: evidence for strong dipolar interaction with paramagnetic centers in the S-1 and S-2 states
(2004) In Physical Chemistry Chemical Physics 6(20). p.4890-4896- Abstract
- Inversion recovery (T-1) and microwave power saturation studies have been performed, between 4 and 25 K, on the EPR signal from the stable tyrosyl radical, Y-D(.), in photosystem II core complex preparations from higher plants. Measurements are reported from the dark stable S-1 and first turnover S-2 states of the photosystem catalytic Mn cluster and in two cryoprotectant regimes; sucrose and ethylene glycol/glycerol. The inversion recovery kinetics show a dominant, non exponential decay component which is well described by a through space dipolar relaxation model, with a weak exponential decay background (similar toan order of magnitude less than the dipolar rate). The dipolar relaxation rate is only modestly temperature dependent and... (More)
- Inversion recovery (T-1) and microwave power saturation studies have been performed, between 4 and 25 K, on the EPR signal from the stable tyrosyl radical, Y-D(.), in photosystem II core complex preparations from higher plants. Measurements are reported from the dark stable S-1 and first turnover S-2 states of the photosystem catalytic Mn cluster and in two cryoprotectant regimes; sucrose and ethylene glycol/glycerol. The inversion recovery kinetics show a dominant, non exponential decay component which is well described by a through space dipolar relaxation model, with a weak exponential decay background (similar toan order of magnitude less than the dipolar rate). The dipolar relaxation rate is only modestly temperature dependent and shows no consistent dependence on S state or cryoprotectant. In contrast, the background rate shows a S state dependence, consistent with an interaction between Y-D(.) and the Mn cluster in the multiline S-2 state, over a distance of similar to30 Angstrom. The fraction of centers exhibiting the dipolar relaxation component appears to be temperature dependent, but S state independent and consistent with the presence of a fast relaxing species interacting with Y-D(.). The present results and the possible nature of this interacting species are discussed in comparison with earlier Y-D(.) relaxation studies on photosystem II membrane samples. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/138678
- author
- Mamedov, Fikret LU ; Smith, P J ; Styring, Stenbjörn LU and Pace, R J
- organization
- publishing date
- 2004
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physical Chemistry Chemical Physics
- volume
- 6
- issue
- 20
- pages
- 4890 - 4896
- publisher
- Royal Society of Chemistry
- external identifiers
-
- wos:000224755500023
- scopus:8144230859
- ISSN
- 1463-9084
- DOI
- 10.1039/b407329k
- language
- English
- LU publication?
- yes
- id
- ad2c55ef-69d4-4e5d-b4bb-e06b3d05d4b9 (old id 138678)
- date added to LUP
- 2016-04-01 16:09:10
- date last changed
- 2022-01-28 17:39:09
@article{ad2c55ef-69d4-4e5d-b4bb-e06b3d05d4b9, abstract = {{Inversion recovery (T-1) and microwave power saturation studies have been performed, between 4 and 25 K, on the EPR signal from the stable tyrosyl radical, Y-D(.), in photosystem II core complex preparations from higher plants. Measurements are reported from the dark stable S-1 and first turnover S-2 states of the photosystem catalytic Mn cluster and in two cryoprotectant regimes; sucrose and ethylene glycol/glycerol. The inversion recovery kinetics show a dominant, non exponential decay component which is well described by a through space dipolar relaxation model, with a weak exponential decay background (similar toan order of magnitude less than the dipolar rate). The dipolar relaxation rate is only modestly temperature dependent and shows no consistent dependence on S state or cryoprotectant. In contrast, the background rate shows a S state dependence, consistent with an interaction between Y-D(.) and the Mn cluster in the multiline S-2 state, over a distance of similar to30 Angstrom. The fraction of centers exhibiting the dipolar relaxation component appears to be temperature dependent, but S state independent and consistent with the presence of a fast relaxing species interacting with Y-D(.). The present results and the possible nature of this interacting species are discussed in comparison with earlier Y-D(.) relaxation studies on photosystem II membrane samples.}}, author = {{Mamedov, Fikret and Smith, P J and Styring, Stenbjörn and Pace, R J}}, issn = {{1463-9084}}, language = {{eng}}, number = {{20}}, pages = {{4890--4896}}, publisher = {{Royal Society of Chemistry}}, series = {{Physical Chemistry Chemical Physics}}, title = {{Relaxation behaviour of the tyrosine Y-D radical in photosystem II: evidence for strong dipolar interaction with paramagnetic centers in the S-1 and S-2 states}}, url = {{http://dx.doi.org/10.1039/b407329k}}, doi = {{10.1039/b407329k}}, volume = {{6}}, year = {{2004}}, }