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首页> 外文期刊>Biochemistry >Time-resolved absorption and emission show that the CP43' antenna ring of iron-stressed synechocystis sp. PCC6803 is efficiently coupled to the photosystem I reaction center core.
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Time-resolved absorption and emission show that the CP43' antenna ring of iron-stressed synechocystis sp. PCC6803 is efficiently coupled to the photosystem I reaction center core.

机译：时间分辨的吸收和发射表明，CP43'天线环的铁胁迫的突触囊藻。 PCC6803有效地耦合到光系统I反应中心核心。

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摘要

Excitation energy transfer and trapping processes in an iron stress-induced supercomplex of photosystem I from the cyanobacterium Synechocystis sp. PCC6803 were studied by time-resolved absorption and fluorescence spectroscopy on femtosecond and picosecond time scales. The data provide evidence that the energy transfer dynamics of the CP43'-PSI supercomplex are consistent with energy transfer processes that occur in the Chl a network of the PSI trimer antenna. The most significant absorbance changes in the CP43'-PSI supercomplex are observed within the first several picoseconds after the excitation into the spectral region of CP43' absorption (665 nm). The difference time-resolved spectra (DeltaDeltaA) resulting from subtraction of the PSI trimer kinetic data from the CP43'-PSI supercomplex data indicate three energy transfer processes with time constants of 0.2, 1.7, and 10 ps. The 0.2 ps kinetic phase is tentatively interpreted as arising from energy transfer processes originating within or between the CP43' complexes. The 1.7 ps phase is interpreted as possibly arising from energy transfer from the CP43' ring to the PSI trimer via closely located clusters of Chl a in CP43' and the PSI core, while the slower 10 ps process might reflect the overall excitation transfer from the CP43' ring to the PSI trimer. These three fast kinetic phases are followed by a 40 ps overall excitation decay in the supercomplex, in contrast to a 25 ps overall decay observed in the trimer complex without CP43'. Excitation of Chl a in both the CP43'-PSI antenna supercomplex and the PSI trimer completely decays within 100 ps, resulting in the formation of P700(+). The data indicate that there is a rapid and efficient energy transfer between the outer antenna ring and the PSI reaction center complex.
机译：激发能量转移和捕获过程中的蓝藻Synechocystis sp。通过时间分辨吸收和荧光光谱研究了飞秒和皮秒时间尺度上的PCC6803。数据提供了证据，证明CP43'-PSI超复合物的能量转移动力学与PSI三聚天线的Chla网络中发生的能量转移过程一致。在激发到CP43'吸收光谱区域（665 nm）之后的最初几皮秒内，观察到CP43'-PSI超复合物中最显着的吸光度变化。从CP43'-PSI超复杂数据中减去PSI三聚体动力学数据得出的时间分辨差异光谱（DeltaDeltaA）表示三个能量传递过程，其时间常数分别为0.2、1.7和10 ps。暂时将0.2 ps的动力学相解释为源自CP43'配合物内部或之间的能量转移过程。 1.7 ps的相位被解释为可能是由于CP43'和PSI磁芯中紧密靠近的Chla簇从CP43'环到PSI三聚体的能量转移而引起的，而10 ps较慢的过程可能反映了从CP43'环到PSI三聚体的能量转移。 CP43'环接到PSI修剪器。在这三个快速动力学阶段之后，超复合物中的总激发衰减为40 ps，而在没有CP43'的三聚体中观察到的总衰减为25 ps。 CP43'-PSI天线超复合体和PSI三聚体中的Chla的激发在100 ps内完全衰减，从而形成P700（+）。数据表明，在外天线环和PSI反应中心复合体之间有快速有效的能量转移。

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