TY - JOUR
T1 - Triplet Delocalization over the Reaction Center Chlorophylls in Photosystem II
AU - Hayase, Taichi
AU - Shimada, Yuichiro
AU - Mitomi, Tatsuya
AU - Nagao, Ryo
AU - Noguchi, Takumi
N1 - Funding Information:
This study was supported by JSPS KAKENHI Grant Number JP22K19270 and Ohsumi Frontier Science Foundation (to T.N.). The computation was performed using Research Center for Computational Science, Okazaki, Japan (Project: 22-IMS-C084).
Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023
Y1 - 2023
N2 - The triplet state of chlorophyll formed by charge recombination in photosystem II (PSII) is a precursor of harmful singlet oxygen. Although main localization of the triplet state on the monomeric chlorophyll, ChlD1, at cryogenic temperatures has been suggested, how the triplet state is delocalized on other chlorophylls remains unclear. Here, we investigated the distribution of the triplet state of chlorophyll in PSII using light-induced Fourier transform infrared (FTIR) difference spectroscopy. Measurements of triplet-minus-singlet FTIR difference spectra with PSII core complexes from cyanobacterial mutants, D1-V157H, D2-V156H, D2-H197A, and D1-H198A, in which the interactions of the 131-keto C═O groups of the reaction center chlorophylls, PD1, PD2, ChlD1, and ChlD2, respectively, were perturbed, identified the 131-keto C═O bands of the individual chlorophylls and showed that the triplet state is delocalized over all of these chlorophylls. It is suggested that the triplet delocalization plays important roles in the photoprotection and photodamage mechanisms in PSII.
AB - The triplet state of chlorophyll formed by charge recombination in photosystem II (PSII) is a precursor of harmful singlet oxygen. Although main localization of the triplet state on the monomeric chlorophyll, ChlD1, at cryogenic temperatures has been suggested, how the triplet state is delocalized on other chlorophylls remains unclear. Here, we investigated the distribution of the triplet state of chlorophyll in PSII using light-induced Fourier transform infrared (FTIR) difference spectroscopy. Measurements of triplet-minus-singlet FTIR difference spectra with PSII core complexes from cyanobacterial mutants, D1-V157H, D2-V156H, D2-H197A, and D1-H198A, in which the interactions of the 131-keto C═O groups of the reaction center chlorophylls, PD1, PD2, ChlD1, and ChlD2, respectively, were perturbed, identified the 131-keto C═O bands of the individual chlorophylls and showed that the triplet state is delocalized over all of these chlorophylls. It is suggested that the triplet delocalization plays important roles in the photoprotection and photodamage mechanisms in PSII.
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U2 - 10.1021/acs.jpcb.3c00139
DO - 10.1021/acs.jpcb.3c00139
M3 - Article
C2 - 36809007
AN - SCOPUS:85148903903
SN - 1520-6106
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
ER -