Akimoto Seiji, Teshigahara Ayaka, Yokono Makio, Mimuro Mamoru, Nagao Ryo, Tomo Tatsuya
Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan; Graduate School of Science, Kobe University, Kobe 657-8501, Japan; CREST, Japan Science and Technology Agency (JST), Kobe 657-8501, Japan.
Graduate School of Science, Kobe University, Kobe 657-8501, Japan.
Biochim Biophys Acta. 2014 Sep;1837(9):1514-21. doi: 10.1016/j.bbabio.2014.02.002. Epub 2014 Feb 12.
In algae, light-harvesting complexes contain specific chlorophylls (Chls) and keto-carotenoids; Chl a, Chl c, and fucoxanthin (Fx) in diatoms and brown algae; Chl a, Chl c, and peridinin in photosynthetic dinoflagellates; and Chl a, Chl b, and siphonaxanthin in green algae. The Fx-Chl a/c-protein (FCP) complex from the diatom Chaetoceros gracilis contains Chl c1, Chl c2, and the keto-carotenoid, Fx, as antenna pigments, in addition to Chl a. In the present study, we investigated energy transfer in the FCP complex associated with photosystem II (FCPII) of C. gracilis. For these investigations, we analyzed time-resolved fluorescence spectra, fluorescence rise and decay curves, and time-resolved fluorescence anisotropy data. Chl a exhibited different energy forms with fluorescence peaks ranging from 677 nm to 688 nm. Fx transferred excitation energy to lower-energy Chl a with a time constant of 300fs. Chl c transferred excitation energy to Chl a with time constants of 500-600fs (intra-complex transfer), 600-700fs (intra-complex transfer), and 4-6ps (inter-complex transfer). The latter process made a greater contribution to total Chl c-to-Chl a transfer in intact cells of C. gracilis than in the isolated FCPII complexes. The lower-energy Chl a received excitation energy from Fx and transferred the energy to higher-energy Chl a. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.
在藻类中，光捕获复合体包含特定的叶绿素（Chls）和酮类胡萝卜素；硅藻和褐藻中的叶绿素a、叶绿素c和岩藻黄素（Fx）；光合甲藻中的叶绿素a、叶绿素c和多甲藻素；以及绿藻中的叶绿素a、叶绿素b和管鞭藻黄素。来自纤细角毛藻的Fx - 叶绿素a/c - 蛋白（FCP）复合体除了含有叶绿素a外，还含有叶绿素c1、叶绿素c2和酮类胡萝卜素Fx作为天线色素。在本研究中，我们研究了与纤细角毛藻光系统II（FCPII）相关的FCP复合体中的能量转移。为了进行这些研究，我们分析了时间分辨荧光光谱、荧光上升和衰减曲线以及时间分辨荧光各向异性数据。叶绿素a表现出不同的能量形式，荧光峰范围为677纳米至688纳米。Fx以300飞秒的时间常数将激发能转移到能量较低的叶绿素a上。叶绿素c以500 - 600飞秒（复合体内转移）、600 - 700飞秒（复合体内转移）和4 - 6皮秒（复合体间转移）的时间常数将激发能转移到叶绿素a上。后一过程对完整的纤细角毛藻细胞中叶绿素c到叶绿素a的总转移贡献比在分离的FCPII复合体中更大。能量较低的叶绿素a从Fx接收激发能并将能量转移到能量较高的叶绿素a上。本文是名为：可持续性光合作用研究：生产清洁能源的关键的特刊的一部分。
