title: Damage to the oxygen-evolving complex by superoxide anion, hydrogen peroxide, and hydroxyl radical in photoinhibition of photosystem II.
abstract: Under strong illumination of a photosystem II (PSII) membrane, endogenous superoxide anion, hydrogen peroxide, and hydroxyl radical were successively produced. These compounds then cooperatively resulted in a release of manganese from the oxygen-evolving complex (OEC) and an inhibition of oxygen evolution activity. The OEC inactivation was initiated by an acceptor-side generated superoxide anion, and hydrogen peroxide was most probably responsible for the transportation of reactive oxygen species (ROS) across the PSII membrane from the acceptor-side to the donor-side. Besides ROS being generated in the acceptor-side induced manganese loss; there may also be a ROS-independent manganese loss in the OEC of PSII. Both superoxide anion and hydroxyl radical located inside the PSII membrane were directly identified by a spin trapping-electron spin resonance (ESR) method in combination with a lipophilic spin trap, 5-(diethoxyphosphoryl)-5-phenethyl-1-pyrroline N-oxide (DEPPEPO). The endogenous hydrogen peroxide production was examined by oxidation of thiobenzamide.
authors.affiliation: State Key laboratory for Structural Chemistry of Unstable and Stable Species, Center for Molecular Science, Institute of Chemistry, The Chinese Academy of Sciences, Beijing, 100080, China.
authors.forename: Yu Guang
authors.initials: YG
authors.lastname: Song
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Lan Fen
authors.initials: LF
authors.lastname: Wang
authors.forename: Mai He
authors.initials: MH
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D017665:Hydroxyl Radical / Q000494:pharmacology*; D007700:Kinetics; D008027:Light; D010100:Oxygen / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000187:drug effects / Q000502:physiology*; D018724:Spinacia oleracea / Q000378:metabolism* / Q000528:radiation effects; D013481:Superoxides / Q000494:pharmacology*
chemical_list: D045332:Photosystem II Protein Complex; D013481:Superoxides; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D010100:Oxygen