The role of metals in production and scavenging of reactive oxygen species in photosystem II

Plant Cell Physiol. 2014 Jul;55(7):1224-32. doi: 10.1093/pcp/pcu053. Epub 2014 Apr 26.


Metal ions play a crucial role in enzymatic reactions in all photosynthetic organisms such as cyanobacteria, algae and plants. It well known that metal ions maintain the binding of substrate in the active site of the metalloenzymes and control the redox activity of the metalloenzyme in the enzymatic reaction. A large pigment-protein complex, PSII, known to serve as a water-plastoquinone oxidoreductase, contains three metal centers comprising non-heme iron, heme iron of Cyt b559 and the water-splitting manganese complex. Metal ions bound to PSII proteins maintain the electron transport from water to plastoquinone and regulate the pro-oxidant and antioxidant activity in PSII. In this review, attention is focused on the role of PSII metal centers in (i) the formation of superoxide anion and hydroxyl radicals by sequential one-electron reduction of molecular oxygen and the formation of hydrogen peroxide by incomplete two-electron oxidation of water; and (ii) the elimination of superoxide anion radical by one-electron oxidation and reduction (superoxide dismutase activity) and of hydrogen peroxide by two-electron oxidation and reduction (catalase activity). The balance between the formation and elimination of reactive oxygen species by PSII metal centers is discussed as an important aspect in the prevention of photo-oxidative damage of PSII proteins and lipids.

Keywords: Cytochrome b559; Non-heme iron; Photo-oxidative damage; Photosystem II; Reactive oxygen species; Water-splitting manganese complex.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Catalytic Domain
  • Cyanobacteria / enzymology*
  • Cytochrome b Group / chemistry
  • Cytochrome b Group / metabolism
  • Free Radical Scavengers / metabolism*
  • Iron / metabolism
  • Manganese / metabolism
  • Metals / metabolism*
  • Models, Molecular
  • Oxidation-Reduction
  • Oxygen / metabolism
  • Photosystem II Protein Complex / chemistry
  • Photosystem II Protein Complex / metabolism*
  • Plants / enzymology*
  • Reactive Oxygen Species / metabolism*
  • Water / metabolism


  • Cytochrome b Group
  • Free Radical Scavengers
  • Metals
  • Photosystem II Protein Complex
  • Reactive Oxygen Species
  • Water
  • Manganese
  • cytochrome b559
  • Iron
  • Oxygen