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Electrogenic reduction of the primary electron donor P700 + in photosystem I by redox dyes
Author(s) -
Kira N. Gourovskaya,
Mahir D. Mamedov,
Ilya R. Vassiliev,
John H. Golbeck,
Alexey Yu. Semenov
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00994-0
Subject(s) - p700 , redox , photosystem i , chemistry , photochemistry , electron donor , electron , photosynthetic reaction centre , photosystem ii , primary (astronomy) , photosynthesis , electron transfer , inorganic chemistry , biochemistry , physics , catalysis , quantum mechanics , astronomy
The kinetics of reduction of the photo‐oxidized primary electron donor P700 + by redox dyes N,N,N ′, N ′‐tetramethyl‐ p ‐phenylendiamine, 2,6‐dichlorophenol‐indophenol and phenazine methosulfate was studied in proteoliposomes containing Photosystem I complexes from cyanobacteria Synechocystis sp. PCC 6803 using direct electrometrical technique. In the presence of high concentrations of redox dyes, the fast generation of a membrane potential related to electron transfer between P700 and the terminal iron‐sulfur clusters F A /F B was followed by a new electrogenic phase in the millisecond time domain, which contributes approximately 20% to the overall photoelectric response. This phase is ascribed to the vectorial transfer of an electron from the redox dye to the protein‐embedded chlorophyll of P700 + . Since the contribution of this electrogenic phase in the presence of artificial redox dyes is approximately equal to that of the phase observed earlier in the presence of cytochrome c 6 , it is likely that electrogenic reduction of P700 + in vivo occurs due to vectorial electron transfer within RC molecule rather than within the cytochrome c 6 ‐P700 complex.