Andreeva Atanaska, Abarova Silvia, Stoitchkova Katerina, Picorel Rafael, Velitchkova Maya
Department of Condensed Matter Physics, Faculty of Physics, Sofia University, Sofia, Bulgaria.
Photochem Photobiol. 2007 Nov-Dec;83(6):1301-7. doi: 10.1111/j.1751-1097.2007.00136.x.
Photosystem I particles (PSI-200) isolated from spinach leaves were studied by means of absorbance, 77K fluorescence and resonance Raman (RR) spectroscopy. The aim was to obtain better insight into the changes of the pigment spectral properties in those particles during prolonged exposure to high-light intensities and to reveal the involvement of these pigments in the photoprotection of the PSI. During prolonged exposure to high-light intensities of spinach PSI particles, a loss of a significant amount of photosynthetic pigments was observed. It was shown that various pigments exhibited different susceptibility to photodamage. In addition to bleaching of chlorophyll a (Chl a), bleaching of carotenoids was also clearly observed. RR technique allowed us to recognize the type and conformation of photobleached carotenoid molecules. Raman data revealed a nearly full photobleaching of the long-wavelength lutein molecules. The observed similar bleaching rate of the lutein molecules and the most-red shifted long-wavelength Chl a, located in the antenna membrane protein Lhca4, suggested that these molecules are located closely. Our results showed that the photobleached antenna pigments and especially luteins and the most long-wavelength absorbing chlorophylls are involved in photoprotection of PSI core complex.
采用吸光度、77K荧光和共振拉曼光谱对从菠菜叶中分离出的光系统I颗粒（PSI-200）进行了研究。目的是更深入地了解这些颗粒在长时间暴露于高光强度下色素光谱特性的变化，并揭示这些色素在光系统I光保护中的作用。在菠菜光系统I颗粒长时间暴露于高光强度的过程中，观察到大量光合色素损失。结果表明，不同色素对光损伤的敏感性不同。除了叶绿素a（Chl a）漂白外，还清楚地观察到类胡萝卜素的漂白。共振拉曼技术使我们能够识别光漂白类胡萝卜素分子的类型和构象。拉曼数据显示长波长叶黄素分子几乎完全光漂白。观察到叶黄素分子与位于天线膜蛋白Lhca4中红移最大的长波长叶绿素a具有相似的漂白速率，这表明这些分子位置紧密。我们的结果表明，光漂白的天线色素，尤其是叶黄素和吸收最长波长的叶绿素参与了光系统I核心复合物的光保护。
