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Updated: Jan 28, 2026

Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale
Published on: March 14, 2019
Ultrafast Excitation Energy Dynamics in a Diatom Photosystem I-Antenna Complex: A Femtosecond Fluorescence
Ryo Nagao1, Kohei Kagatani2, Yoshifumi Ueno2
1Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan.
Abstract:
Fucoxanthin chlorophyll (Chl) a/ c-binding proteins (FCPs) are unique light-harvesting antennas in diatoms. Recent time-resolved fluorescence analysis of photosystem I with FCP associated (PSI-FCPI) has mainly shown excitation energy transfer among Chls a from FCPI to PSI in tens of picoseconds. However, it remains unclear how each pigment, especially carotenoids and Chl c, in the FCPI is functionally related to the energy transfer in a femtosecond time range. Here, we reveal ultrafast excitation energy transfer mechanism in the PSI-FCPI preparations isolated from a diatom, Chaetoceros gracilis, by means of femtosecond time-resolved fluorescence spectroscopy with an upconversion system. Compared with the fluorescence lifetime components of PSI core-like complexes, the energy transfer of Chl c → Chl a in the FCPI was observed within hundreds of femtoseconds, and the energy in the FCPI was transferred to PSI in ∼2 ps. The comparative fluorescence analyses provide physical insights into the energy transfer machinery within FCPI and from FCPI to PSI.
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