TY - JOUR
T1 - Cryogenic Single-Molecule Spectroscopy of the Primary Electron Acceptor in the Photosynthetic Reaction Center
AU - Kondo, Toru
AU - Mutoh, Risa
AU - Tabe, Hiroaki
AU - Kurisu, Genji
AU - Oh-Oka, Hirozo
AU - Fujiyoshi, Satoru
AU - Matsushita, Michio
N1 - Funding Information:
We thank Dr. Chihiro Azai at Ritsumeikan University for helpful discussions, Dr. Shigeru Itoh at Nagoya University for assistance for the measurement of absorption spectrum at cryogenic temperatures, and Dr. Yutaka Shibata at Tohoku University for helpful comments. This work was supported by Grants-in-Aid for Scientific Research (Nos. 24008402 and 26810003 to T.K., No. 15K21122 to R.M., and No. 18K06153 to H.O.), JST PRESTO (JPMJPR18G7 to T.K.), and JSPS Grants-in-Aid for Scientific Research on Innovative Areas (Nos. 17H05724 and 18H05163 to H.O.).
Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/5/21
Y1 - 2020/5/21
N2 - The photosynthetic reaction center (RC) converts light energy into electrochemical energy. The RC of heliobacteria (hRC) is a primitive homodimeric RC containing 58 bacteriochlorophylls and 2 chlorophyll as. The chlorophyll serves as the primary electron acceptor (Chl a-A0) responsible for light harvesting and charge separation. The single-molecule spectroscopy of Chl a-A0 can be used to investigate heterogeneities of the RC photochemical function, though the low fluorescence quantum yield (0.1%) makes it difficult. Here, we show the fluorescence excitation spectroscopy of individual Chl a-A0s in single hRCs at 6 K. The fluorescence quantum yield and absorption cross section of Chl a-A0 increase 2- and 4-fold, respectively, compared to those at room temperature. The two Chl a-A0s in single hRCs are identified as two distinct peaks in the fluorescence excitation spectrum, exhibiting different excitation polarization dependences. The spectral changes caused by photobleaching indicate the energy transfer across subunits in the hRC.
AB - The photosynthetic reaction center (RC) converts light energy into electrochemical energy. The RC of heliobacteria (hRC) is a primitive homodimeric RC containing 58 bacteriochlorophylls and 2 chlorophyll as. The chlorophyll serves as the primary electron acceptor (Chl a-A0) responsible for light harvesting and charge separation. The single-molecule spectroscopy of Chl a-A0 can be used to investigate heterogeneities of the RC photochemical function, though the low fluorescence quantum yield (0.1%) makes it difficult. Here, we show the fluorescence excitation spectroscopy of individual Chl a-A0s in single hRCs at 6 K. The fluorescence quantum yield and absorption cross section of Chl a-A0 increase 2- and 4-fold, respectively, compared to those at room temperature. The two Chl a-A0s in single hRCs are identified as two distinct peaks in the fluorescence excitation spectrum, exhibiting different excitation polarization dependences. The spectral changes caused by photobleaching indicate the energy transfer across subunits in the hRC.
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U2 - 10.1021/acs.jpclett.0c00891
DO - 10.1021/acs.jpclett.0c00891
M3 - Article
C2 - 32352789
AN - SCOPUS:85085265019
SN - 1948-7185
VL - 11
SP - 3980
EP - 3986
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 10
ER -