EC - Photosystem II

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IntEnz Enzyme Nomenclature


Accepted name:
photosystem II
Systematic name:
H2O:plastoquinone reductase (light-dependent)



Contains chlorophyll a, β-carotene, pheophytin, plastoquinone, a Mn4Ca cluster, heme and non-heme iron. Four successive photoreactions, resulting in a storage of four positive charges, are required to oxidize two water molecules to one oxygen molecule.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
UniProtKB/Swiss-Prot: (389) [show] [UniProt]


  1. Knaff, D. B., Malkin, R., Myron, J. C., Stoller, M.
    The role of plastoquinone and β-carotene in the primary reaction of plant photosystem II.
    Biochim. Biophys. Acta 459: 402-411 (1977). [PMID: 849432]
  2. Guskov, A., Kern, J., Gabdulkhakov, A., Broser, M., Zouni, A., Saenger, W.
    Cyanobacterial photosystem II at 2.9-Å resolution and the role of quinones, lipids, channels and chloride.
    Nat. Struct. Mol. Biol. 16: 334-342 (2009). [PMID: 19219048]

[EC created 2011]