title: Isolation and characterization of oxygen-evolving thylakoid membranes and photosystem II particles from a marine diatom Chaetoceros gracilis.
abstract: Thylakoid membranes retaining high oxygen-evolving activity (about 250 micromol O(2)/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 micromol O(2)/mg Chl/h in the absence and presence of CaCl(2), 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.
authors.affiliation: Department of Biology, Faculty of Science, Tokyo University of Science, Kagurazaka 1-3, Tokyo 162-8601, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Nagao
authors.forename: Akiko
authors.initials: A
authors.lastname: Ishii
authors.forename: Osamu
authors.initials: O
authors.lastname: Tada
authors.forename: Takehiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Naoshi
authors.initials: N
authors.lastname: Dohmae
authors.forename: Akinori
authors.initials: A
authors.lastname: Okumura
authors.forename: Masako
authors.initials: M
authors.lastname: Iwai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takahashi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kashino
authors.forename: Isao
authors.initials: I
authors.lastname: Enami
mesh_terms: D002458:Cell Fractionation; D017377:Diatoms / Q000737:chemistry / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology; D020524:Thylakoids / Q000737:chemistry / Q000378:metabolism*
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010100:Oxygen