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首页> 外文期刊>Biochemistry >Energy transfer in the major intrinsic light-harvesting complex from Amphidinium carterae
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Energy transfer in the major intrinsic light-harvesting complex from Amphidinium carterae

机译：碳弧菌的主要内在光捕获复合体中的能量转移

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Carbonyl carotenoids are important constituents of the antenna complexes of marine organisms. These carotenoids possess an excited state with a charge-transfer character ( intramolecular charge transfer state, ICT), but many details of the carotenoid to chlorophyll energy transfer mechanisms are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to study energy transfer pathways in the intrinsic light-harvesting complex (LHC) of dinoflagellates, which contains the carbonyl carotenoid peridinin. Carotenoid to chlorophyll energy transfer efficiency is about 90% in the 530-550 nm region, where the peridinin S-2 state transfers energy with an efficiency of 25-50%. The rest proceeds via the S-1/ICT channel, and the major S-1/ICT-mediated energy transfer pathway utilizes the relaxed S-1/ICT state and occurs with a time constant of 2.6 ps. Below 525 nm, the overall energy transfer efficiency drops because of light absorption by another carotenoid, diadinoxanthin, that contributes only marginally to energy transfer. Instead, its role is likely to be photoprotection. In addition to the peridinin-Chl-a energy transfer, it was shown that energy transfer also occurs between the two chlorophyll species in LHC, Chl-c(2), and Chl-a. The time constant characterizing the Chl-c2 to Chl-a energy transfer is 1.4 ps. The results demonstrate that the properties of the S1/ICT state specific for carbonyl carotenoids is the key to ensure the effective harvesting of photons in the 500-600 nm region, which is of vital importance to underwater organisms.
机译：羰基类胡萝卜素是海洋生物天线复合物的重要组成部分。这些类胡萝卜素具有带电荷转移特性的激发态（分子内电荷转移态，ICT），但对类胡萝卜素至叶绿素能量转移机制的许多细节仍知之甚少。在这里，我们采用飞秒瞬态吸收光谱法研究了鞭毛藻的内在光捕获复合物（LHC）中的能量传递途径，该鞭毛中含有羰基类胡萝卜素peridinin。在530-550 nm区域，类胡萝卜素到叶绿素的能量转移效率大约为90％，在该区域，peridinin S-2状态以25-50％的效率转移能量。其余的通过S-1 / ICT通道进行，并且主要的S-1 / ICT介导的能量传输路径利用松弛的S-1 / ICT状态，并且以2.6 ps的时间常数发生。在525 nm以下，由于另一种类胡萝卜素二恶英黄嘌呤吸收的光，总的能量转移效率下降，而后者仅对能量转移有很小的贡献。相反，其作用可能是光保护。除了peridinin-Chl-a能量转移外，还表明能量转移也发生在LHC，Chl-c（2）和Chl-a中的两个叶绿素种类之间。 Chl-c2到Chl-a能量转移的时间常数为1.4 ps。结果表明，羰基类胡萝卜素特有的S1 / ICT状态的特性是确保有效收获500-600 nm区域中光子的关键，这对水下生物至关重要。

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