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Electrostatic role of the non‐heme iron complex in bacterial photosynthetic reaction center
Author(s) -
Ishikita Hiroshi,
Knapp Ernst-Walter
Publication year - 2006
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/j.febslet.2006.07.023
Subject(s) - photosynthetic reaction centre , chemistry , redox , electron transfer , heme , photosynthesis , photochemistry , crystallography , inorganic chemistry , biochemistry , enzyme
To elucidate the role of the non‐heme iron complex (Fe‐complex) in the electron transfer (ET) events of bacterial photosynthetic reaction centers (bRC), we calculated redox potentials of primary/secondary quinones Q A/B ( E m (Q A/B )) in the Fe‐depleted bRC. Removing the Fe‐complex, the calculated E m (Q A/B ) are downshifted by ∼220 mV/∼80 mV explaining both the 15‐fold decrease in ET rate from bacteriopheophytin ( H A ‐ ) to Q A and triplet state occurrence in Fe‐depleted bRC. The larger downshift in E m (Q A ) relative to E m (Q B ) increases the driving‐energy for ET from Q A to Q B by 140 meV, in agreement with ∼100 meV increase derived from kinetic studies.