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Excitation energy transfer in the far-red absorbing violaxanthin/vaucheriaxanthin chlorophyll a complex from the eustigmatophyte alga FP5
摘要： This work highlights spectroscopic investigations on a new representative of photosynthetic antenna complexes in the LHC family, a putative violaxanthin/vaucheriaxanthin chlorophyll a (VCP) antenna complex from a freshwater Eustigmatophyte alga FP5. A representative VCP-like complex, named as VCP-B3 was studied with both static and time-resolved spectroscopies with the aim of obtaining a deeper understanding of excitation energy migration within the pigment array of the complex. Compared to other VCP representatives, the absorption spectrum of the VCP-B3 is strongly altered in the range of the chlorophyll a Qy band, and is substantially red-shifted with the longest wavelength absorption band at 707 nm at 77 K. VCP-B3 shows a moderate xanthophyll-to-chlorophyll a efficiency of excitation energy transfer in the 50–60% range, 20–30% lower from comparable VCP complexes from other organisms. Transient absorption studies accompanied by detailed data fitting and simulations support the idea that the xanthophylls that occupy the central part of the complex, complementary to luteins in the LHCII, are violaxanthins. Target analysis suggests that the primary route of xanthophyll-to-chlorophyll a energy transfer occurs via the xanthophyll S1 state.
关键词： Chlorophyll a,Light-harvesting complex,Transient absorption,Violaxanthin,Photosynthesis,Vaucheriaxanthin
更新于2025-11-19 16:46:39
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Simulating Fluorescence Detected Two-Dimensional Electronic Spectroscopy of Multi-Chromophoric Systems
摘要： We present a theory for modeling fluorescence detected two-dimensional electronic spectroscopy of multichromophoric systems. The theory is tested by comparison of the predicted spectra of the light-harvesting complex LH2 with experimental data. A qualitative explanation of the strong cross-peaks as compared to conventional two-dimensional electronic spectra is given. The strong cross-peaks are attributed to the clean ground state signal that is revealed when the annihilation of exciton pairs created on the same LH2 complex cancels oppositely-signed signals from the doubly-excited state. This annihilation process occurs much faster than the non-radiative relaxation. Furthermore, the lineshape difference is attributed to slow dynamics, exciton delocalization within the bands and intraband exciton-exciton annihilation. This is in line with existing theories presented for model systems. We further propose the use of time-resolved fluorescence detected two-dimensional spectroscopy to study state resolved exciton-exciton annihilation.
关键词： fluorescence detected two-dimensional electronic spectroscopy,multichromophoric systems,light-harvesting complex LH2,exciton-exciton annihilation,time-resolved fluorescence detected two-dimensional spectroscopy
更新于2025-09-04 15:30:14