Chlorophyll a dimer: a possible primary electron donor for the photosystem II.
In the photosynthetic membrane, there is a particular aggregated state for the chlorophyll a (Chl a) molecules with a specific arrangement responsible for the high efficiency of energy conversion. Chl a monolayers, transferred onto solid substrates, are systems that potentially can mimic the packing of the in vivo system. The association of Chl a in the monolayer results in the formation of dimers with an average size of 3.00 +/- 0.15 nm. Considering the organization of the dimers, we assume that P680 is a dimer with the (anti) parallel transition moments of the constituent. The Chl a macrocycles most likely are tilted to each other by 30 degrees with respect to the membrane plane.
Boussaad
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P.O. Box 249118, Department of Chemistry, University of Miami, Coral Gables, FL 33124-0431, USA.
Tazi
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Leblanc
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