부산대학교 도서관

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 Chl.sub.Z 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 Chl.sub.ZD1 work as the 695-nm emitting Chl and the quenching site, respectively, and (B) Chl29 and the oxidized Chl.sub.ZD2 work as the 695-nm emitting Chl and the quenching site, respectively.
Author(s): Ahmed Mohamed [sup.1] [sup.2], Shunsuke Nishi [sup.3], Keisuke Kawakami [sup.4], Jian-Ren Shen [sup.5], Shigeru Itoh [sup.3], Hiroshi Fukumura [sup.1] [sup.6], Yutaka Shibata [sup.1] Author Affiliations: (1) grid.69566.3a, 0000 0001 [...]