Isolation and characterization of oxygen-evolving thylakoid membranes and Photosystem II particles from a marine diatom Chaetoceros gracilis

Ryo Nagao, Akiko Ishii, Osamu Tada, Takehiro Suzuki, Naoshi Dohmae, Akinori Okumura, Masako Iwai, Takeshi Takahashi, Yasuhiro Kashino, Isao Enami

Research output: Contribution to journalArticle

66 Citations (Scopus)


Thylakoid membranes retaining high oxygen-evolving activity (about 250 μmol O2/mg Chl/h) were prepared from a marine centric diatom, Chaetoceros gracilis, after disruption of the cells by freeze-thawing. We also succeeded in purification of Photosystem II (PSII) particles by differential centrifugation of the thylakoid membranes after treatment with 1% Triton X-100. The diatom PSII particles showed an oxygen-evolving activity of 850 and 1045 μmol O2/mg Chl/h in the absence and presence of CaCl2, respectively. The PSII particles contained fucoxanthin chlorophyll a/c-binding proteins in addition to main intrinsic proteins of CP47, CP43, D2, D1, cytochrome b559, and the antenna size was estimated to be 229 Chl a per 2 molecules of pheophytin. Five extrinsic proteins were stoichiometrically released from the diatom PSII particles by alkaline Tris-treatment. Among these five extrinsic proteins, four proteins were red algal-type extrinsic proteins, namely, PsbO, PsbQ', PsbV and PsbU, whereas the other one was a novel, hypothetical protein. This is the first report on isolation and characterization of diatom PSII particles that are highly active in oxygen evolution and retain the full set of extrinsic proteins including an unknown protein.

Original languageEnglish
Pages (from-to)1353-1362
Number of pages10
JournalBiochimica et Biophysica Acta - Bioenergetics
Issue number12
Publication statusPublished - Dec 2007
Externally publishedYes



  • Chaetoceros gracilis
  • Diatom
  • Extrinsic protein
  • Oxygen evolution
  • Photosystem II

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this