Metallo-radical hypothesis for photoassembly of (Mn)4-cluster of photosynthetic oxygen evolving complex.
A new hypothetical mechanism is proposed for photoassembly of the (Mn)4-cluster of the photosynthetic oxygen evolving complex (OEC). In this process, a neutral radical of Y(Z) tyrosine plays a role in oxidizing Mn2+ associated with an apo-OEC, and also in abstracting a proton from a water molecule bound to the Mn2+ ion, together with D1-His190. This is in a similar fashion to the metallo-radical mechanism proposed for photosynthetic water oxidation by the (Mn)4-cluster. The model insists that a common mechanism participates in the photoassembly of the (Mn)4-cluster and the photosynthetic water oxidation.
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Laboratory for Photo-Biology, RIKEN Photodynamics Research Center, The Institute of Physical and Chemical Research, 519-1399 Aoba, Aramaki, Sendai 980-0845, Aoba, Japan. takaaki@postman.riken.go.jp
D005609:Free Radicals; D007700:Kinetics; D008345:Manganese / Q000737:chemistry*; D008956:Models, Chemical; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010777:Photochemistry; D017785:Photons; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry
D005609:Free Radicals; D009942:Organometallic Compounds; D045322:Photosynthetic Reaction Center Complex Proteins; C114979:tyrosyl radical YZ; D014867:Water; D014443:Tyrosine; D008345:Manganese; D010100:Oxygen