Photoaffinity labeling of the phylloquinone-binding polypeptides by 2-azidoanthraquinone in photosystem I particles

Masayo Iwaki, Masaaki Takahashi, Keizo Shimada, Yuichiro Takahashi, Shigeru Itoh

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8 Citations (Scopus)


A photoaffinity label, 2-azido-9,10-anthraquinone, binds at the quinone-binding (Qφ) site with high affinity and can substitute for the secondary acceptor, phylloquinone, in photosystem I reaction center of spinach. Phylloquinone-depleted photosystem I particles reconstituted with azido-[3H]anthraquinone were illuminated with UV light and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The large core polypeptides (psaA and/or psaB) were selectively labeled. The labeling was competitively inhibited in the presence of anthraquinone. These results indicate that the Qφ site is located on psaA or psaB polypeptides.

Original languageEnglish
Pages (from-to)27-30
Number of pages4
JournalFEBS Letters
Issue number1
Publication statusPublished - Nov 2 1992



  • Electron transfer
  • Photoaffinity label
  • Photosystem I
  • Phylloquinone (vitamin K)
  • Reaction center

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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