Isolation and characterization of oxygen-evolving thylakoid membranes and Photosystem II particles from a marine diatom Chaetoceros gracilis
Isolation and characterization of oxygen-evolving thylakoid membranes and Photosystem II particles from a marine diatom Chaetoceros gracilis
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DOI：
10.1016/j.bbabio.2007.10.007
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发表时间：
2007-12-01
影响因子：
4.3
通讯作者：
Enami, Isao
中科院分区：
文献类型：
--
作者：
Nagao, Ryo;Ishii, Akiko;Enami, Isao
以海洋为中心的硅藻--纤细角藻(Chaetoceros Gracilis)经冻融破碎后，制得具有较高放氧活性的类囊体膜(约250µmolO-2/mg Chl/h)。我们还用1%Triton X-100处理类囊体膜，通过差速离心法成功地纯化了光系统11(PSII)颗粒。硅藻PSII颗粒在无CaCl2和有CaCl2存在下的放氧活性分别为850和1045mmolO-2/mg Chl/h。PSII颗粒除含有CP47、CP43、D2、D1、细胞色素b559等主要内源蛋白外，还含有岩藻黄质叶绿素a/c结合蛋白，每2个叶绿素分子的触角大小为229Chla。通过碱性Tris处理，从硅藻PSII颗粒中按化学计量比释放了5种外源蛋白。在这5个外源蛋白中，有4个是红藻型外源蛋白，分别是PsbO、PsbQ‘、PsbV和PsbU，另一个是新发现的假想蛋白。这是有关硅藻PSII颗粒的分离和鉴定的首次报道，这些颗粒在放氧过程中高度活跃，并保留包括未知蛋白质在内的全套外源蛋白质。(C)2007 Elsevier B.V.保留所有权利。
Thylakoid membranes retaining high oxygen-evolving activity (about 250 mu mol 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 11 (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 mu mol O-2/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. (C) 2007 Elsevier B.V. All rights reserved.