Proton-coupled electron-transfer processes in photosystem II probed by highly resolved g -anisotropy of redox-active tyrosine YZ

Hideto Matsuoka, Jian Ren Shen, Asako Kawamori, Kei Nishiyama, Yasunori Ohba, Seigo Yamauchi

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    21 Citations (Scopus)

    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 Y Z 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.

    Original languageEnglish
    Pages (from-to)4655-4660
    Number of pages6
    JournalJournal of the American Chemical Society
    Volume133
    Issue number12
    DOIs
    Publication statusPublished - Mar 30 2011

    ASJC Scopus subject areas

    • Catalysis
    • Chemistry(all)
    • Biochemistry
    • Colloid and Surface Chemistry

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