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Proton-Coupled Electron-Transfer Processes in Photosystem II Probed by Highly Resolved g-Anisotropy of Redox-Active Tyrosine Yz.
- Source :
-
Journal of the American Chemical Society . 3/30/2011, Vol. 133 Issue 12, p4655-4660. 6p. - Publication Year :
- 2011
-
Abstract
- The oxidation of a redox-active tyrosine residue YZ in photosystem II (PSII) is coupled with proton transfer to a hydrogen-bonded D1-His190 residue. Because of the apparent proximity of YZ to the water-oxidizing complex and its redox activity, it is believed that YZ plays a significant role in water oxidation in PSII. We investigated the g-anisotropy of the tyrosine radical YZ∙ to provide insight into the mechanism of YZ∙ proton-coupled electron transfer in Mn-depleted PSII. The anisotropy was highly resolved by electron paramagnetic resonance spectroscopy at the W-band (94.9 GHz) using PSII single crystals. The gX-component along the phenolic C-O bond of YZ∙ was calculated by density functional theory (DFT). It was concluded from the highly resolved g-anisotropy that YZ loses a phenol proton to D1-His190 upon tyrosine oxidation, and D1-His190 redonates the same proton back to YZ∙ upon reduction. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00027863
- Volume :
- 133
- Issue :
- 12
- Database :
- Academic Search Index
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 62170733
- Full Text :
- https://doi.org/10.1021/ja2000566