Ilagan Robielyn P, Shima Sumie, Melkozernov Alexander, Lin Su, Blankenship Robert E, Sharples Frank P, Hiller Roger G, Birge Robert R, Frank Harry A
Department of Chemistry, 55 North Eagleville Road, University of Connecticut, Storrs, Connecticut 06269-3060, USA.
Biochemistry. 2004 Feb 17;43(6):1478-87. doi: 10.1021/bi0357964.
The main-form (MFPCP) and high-salt (HSPCP) peridinin-chlorophyll a proteins from the dinoflagellate Amphidinium carterae were investigated using absorption, fluorescence, fluorescence excitation, two-photon, and fast-transient optical spectroscopy. Pigment analysis has demonstrated previously that MFPCP contains eight peridinins and two chlorophyll (Chl) a molecules, whereas HSPCP has six peridinins and two Chl a molecules [Sharples, F. P., et al. (1996) Biochim. Biophys. Acta 1276, 117-123]. Absorption spectra of the complexes were recorded at 10 K and analyzed in the 400-600 nm region by summing the individual 10 K spectra of Chl a and peridinin recorded in 2-MTHF. The absorption spectral profiles of the complexes in the Q(y) region between 650 and 700 nm were fit using Gaussian functions. The absorption and fluorescence spectra from both complexes exhibit several distinguishing features that become evident only at cryogenic temperatures. In particular, at low temperatures the Q(y) transitions of the Chls bound in the HSPCP complex are split into two well-resolved bands. Fluorescence excitation spectroscopy has revealed that the peridinin-to-Chl a energy transfer efficiency is high (>95%). Transient absorption spectroscopy has been used to measure the rate of energy transfer between the two bound Chls which is a factor of 2.9 slower in HSPCP than in MFPCP. The kinetic data are interpreted in terms of the Förster mechanism describing energy transfer between weakly coupled, spatially fixed, donor-acceptor Chl a molecules. The study provides insight into the molecular factors that control energy transfer in this class of light-harvesting pigment-protein complexes.
利用吸收光谱、荧光光谱、荧光激发光谱、双光子光谱和快速瞬态光谱，对来自双鞭毛藻卡特亚扁藻的主要形式（MFPCP）和高盐形式（HSPCP）的多甲藻素-叶绿素a蛋白进行了研究。先前的色素分析表明，MFPCP含有八个多甲藻素和两个叶绿素（Chl）a分子，而HSPCP含有六个多甲藻素和两个Chl a分子[Sharples, F. P., 等人（1996年）《生物化学与生物物理学报》1276, 117 - 123]。在10 K下记录复合物的吸收光谱，并通过对在2 - MTHF中记录的Chl a和多甲藻素的单个10 K光谱求和，在400 - 600 nm区域进行分析。使用高斯函数拟合650至700 nm之间Q(y)区域中复合物的吸收光谱轮廓。两种复合物的吸收光谱和荧光光谱都表现出几个仅在低温下才明显的显著特征。特别是，在低温下，HSPCP复合物中结合的Chls的Q(y)跃迁分裂为两个分辨率良好的谱带。荧光激发光谱表明，多甲藻素到Chl a的能量转移效率很高（>95%）。瞬态吸收光谱已用于测量两个结合的Chls之间的能量转移速率，HSPCP中的能量转移速率比MFPCP慢2.9倍。动力学数据根据描述弱耦合、空间固定的供体 - 受体Chl a分子之间能量转移的Förster机制进行解释。该研究深入了解了控制这类光捕获色素 - 蛋白质复合物中能量转移的分子因素。
