Biological Research Centre, Szeged, Temesvári krt. 62, Szeged, 6726, Hungary.
ELI-ALPS, ELI-HU Nonprofit Ltd., Wolfgang Sandner u. 3, Szeged, 6728, Hungary.
Photosynth Res. 2020 May;144(2):247-259. doi: 10.1007/s11120-020-00719-w. Epub 2020 Feb 19.
Excitation energy transfer (EET) and trapping in Anabaena variabilis (PCC 7120) intact cells, isolated phycobilisomes (PBS) and photosystem I (PSI) complexes have been studied by picosecond time-resolved fluorescence spectroscopy at room temperature. Global analysis of the time-resolved fluorescence kinetics revealed two lifetimes of spectral equilibration in the isolated PBS, 30-35 ps and 110-130 ps, assigned primarily to energy transfer within the rods and between the rods and the allophycocyanin core, respectively. An additional intrinsic kinetic component with a lifetime of 500-700 ps was found, representing non-radiative decay or energy transfer in the core. Isolated tetrameric PSI complexes exhibited biexponential fluorescence decay kinetics with lifetimes of about 10 ps and 40 ps, representing equilibration between the bulk antenna chlorophylls with low-energy "red" states and trapping of the equilibrated excitations, respectively. The cascade of EET in the PBS and in PSI could be resolved in intact filaments as well. Virtually all energy absorbed by the PBS was transferred to the photosystems on a timescale of 180-190 ps.
室温下通过皮秒时间分辨荧光光谱法研究了 Anabaena variabilis (PCC 7120)完整细胞、分离的藻胆体 (PBS) 和光系统 I (PSI) 复合物中的激发能转移 (EET) 和俘获。对时间分辨荧光动力学的全局分析表明，在分离的 PBS 中存在两种光谱平衡的寿命，分别为 30-35 ps 和 110-130 ps，主要归因于棒之间和棒与别藻蓝蛋白核心之间的能量转移。发现了另一个具有 500-700 ps 寿命的固有动力学组件，代表核心中的非辐射衰减或能量转移。分离的四聚 PSI 复合物表现出双指数荧光衰减动力学，寿命约为 10 ps 和 40 ps，分别代表低能量“红色”状态的大量天线叶绿素之间的平衡和平衡激发的俘获。PBS 和 PSI 中的 EET 级联也可以在完整的长丝中分辨出来。实际上，PBS 吸收的所有能量都在 180-190 ps 的时间尺度上转移到光系统。
