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- Title
Exciton quenching by oxidized chlorophyll Z across the two adjacent monomers in a photosystem II core dimer.
- Authors
Mohamed, Ahmed; Nishi, Shunsuke; Kawakami, Keisuke; Shen, Jian-Ren; Itoh, Shigeru; Fukumura, Hiroshi; Shibata, Yutaka
- Abstract
This study aimed to clarify (1) which pigment in a photosystem II (PSII) core complex is responsible for the 695-nm emission at 77 K and (2) the molecular basis for the oxidation-induced fluorescence quenching in PSII. Picosecond time-resolved fluorescence dynamics was compared between the dimeric and monomeric PSII with and without addition of an oxidant. The results indicated that the excitation-energy flow to the 695-nm-emitting chlorophyll (Chl) at 36 K and 77 K was hindered upon monomerization, clearly demonstrating significant exciton migration from the Chls on one monomer to the 695-nm-emitting pigment on the adjacent monomer. Oxidation of the redox-active Chl, which is named ChlZ caused almost equal quenching of the 684-nm and 695-nm emission bands in the dimer, and lower quenching of the 695-nm band in the monomer. These results suggested two possible scenarios responsible for the 695-nm emission band: (A) Chl11-13 pair and the oxidized ChlZD1 work as the 695-nm emitting Chl and the quenching site, respectively, and (B) Chl29 and the oxidized ChlZD2 work as the 695-nm emitting Chl and the quenching site, respectively.
- Subjects
PHOTOSYSTEMS; CHLOROPHYLL spectra; MONOMERS; FLUORESCENCE quenching; CHLOROPHYLL; TIME-resolved spectroscopy; FLUORESCENCE spectroscopy
- Publication
Photosynthesis Research, 2022, Vol 154, Issue 3, p277
- ISSN
0166-8595
- Publication type
Article
- DOI
10.1007/s11120-022-00948-1