Electrogenicity accompanies photoreduction of the iron-sulfur clusters F(A) and F(B) in photosystem I.
Photovoltage responses accompanying electron transfer on the acceptor side of photosystem I (PS I) were investigated in proteoliposomes containing PS I complexes from the cyanobacterium Synechococcus sp. PCC 6301 using a direct electrometrical technique. The relative contributions of the F(X) --> F(B) and the F(X) --> F(A) electron transfer reactions to the overall electrogenicity were elucidated by comparing the sodium dithionite-induced decrease in the magnitude of the total photoelectric responses in control and in F(B)-less (HgCl2-treated) PS I complexes. The results obtained suggest that the electrogenesis on the acceptor side of PS I is related to electron transfers between both F(X) and F(A) and F(A) and F(B). Based on the electrogenic nature of the latter reaction in PS I complexes, we conclude that F(A) rather than F(B) is the acceptor proximal to F(X).
Mamedov
M D
MD
Department of Photobiochemistry, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
Gourovskaya
K N
KN
Vassiliev
I R
IR
Golbeck
J H
JH
Sememov AYu
D000458:Cyanobacteria / Q000378:metabolism*; D004579:Electron Transport; D058085:Iron Compounds / Q000378:metabolism; D010084:Oxidation-Reduction; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism; D013457:Sulfur Compounds / Q000378:metabolism
D058085:Iron Compounds; D045322:Photosynthetic Reaction Center Complex Proteins; D011510:Proteolipids; D013457:Sulfur Compounds; C020485:proteoliposomes