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Iron—quinone interactions in the electron acceptor region of bacterial photosynthetic reaction centers
Author(s) -
Wraight C.A.
Publication year - 1978
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 - 10.1016/0014-5793(78)81122-3
Subject(s) - quinone , citation , chemistry , electron acceptor , library science , photosynthetic reaction centre , photosynthesis , computer science , stereochemistry , biochemistry
Binary oscillations in electron transfer reactions of quinones on the acceptor side of the photoact have been widely observed in photosynthesis [l--5] . In reaction centers from Rhodopseudomonas sphaeroides this behaviour has been seen by both optical and ESR spectroscopy and can be explained by the concerted activity of two relatively special&d quinones in an acceptor region of the reaction center complex [3,4]. It is well established in bacteria that the primary quinone (QI) is associated with an iron atom [6,7] giving rise to a characteristic and highly distorted ESR signal of the semiquinone [6,8]. A similar ESR spectrum is seen for the semiquinone of the secondary quinone (Qn) showing that this, too, interacts with the iron atom [3]. The function of the iron atom is currently unknown but its removal inhibits electron transfer from QI--QII [ 181. It is shown here that the interaction with the iron is distinctly different for the two quinones. It is also suggested that magnetic coupling may occur between the two semiquinones when both are present which may be significant to the mechanism of electron transfer between them*.