Kinetics of charge separation and A0- --> A1 electron transfer in photosystem I reaction centers.
The charge separation P700*A(0) --> P700(+)A(0)(-) and the subsequent electron transfer from the primary to secondary electron acceptor have been studied by subtracting absorption difference profiles for cyanobacterial photosystem I (PS I) complexes with open and closed reaction centers. Samples were excited at 660 nm, which lies toward the blue edge of the core antenna absorption spectrum. The resulting PS I kinetics were analyzed in terms of the relevant P700, P700(+), A(0), and A(0)(-) absorption spectra. In our kinetic model, the radical pair P700(+)A(0)(-) forms with 1.3 ps rise kinetics after creation of electronically excited P700*. The formation of A(1)(-) via electron transfer from A(0)(-) requires approximately 13 ps. The kinetics of the latter step are appreciably faster than previously estimated by other groups (20--50 ps).
Savikhin
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S
Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA.
Xu
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W
Martinsson
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Chitnis
P R
PR
Struve
W S
WS
D002734:Chlorophyll / Q000378:metabolism*; D003198:Computer Simulation; D016001:Confidence Intervals; D000458:Cyanobacteria / Q000378:metabolism; D004579:Electron Transport; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D008956:Models, Chemical; D016011:Normal Distribution; D010782:Photolysis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D013053:Spectrophotometry / Q000379:methods / Q000706:statistics & numerical data
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D002734:Chlorophyll; C001785:chlorophyll P 700