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Inorganic Fe 2+ formation upon Fe‐S protein thermodestruction in the membranes of thermophilic cyanobacteria: Mössbauer spectroscopy study
Author(s) -
Kaurov Yu.N.,
Novakova A.A.,
Davletshina L.N.,
Aleksandrov A.Yu.,
Khval'kovskaya E.A.,
Semin B.K.,
Belevich N.P.,
Ivanov I.I.,
Rubin A.B.
Publication year - 1999
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(99)00485-8
Subject(s) - ferredoxin , membrane , mössbauer spectroscopy , chemistry , quadrupole splitting , electron transfer , photosystem ii , photosynthesis , photosystem i , thermophile , cyanobacteria , photosystem , electron transport chain , spectroscopy , crystallography , analytical chemistry (journal) , photochemistry , physics , biology , biochemistry , bacteria , enzyme , genetics , chromatography , quantum mechanics
A model description of the Mössbauer spectrum (80 K) of native membranes of the thermophilic cyanobacterium Synechococcus elongatus is suggested on the basis of the known values of quadrupole splitting (Δ E Q ) and isomer shift ( δ Fe ) for the iron‐containing components of the photosynthetic apparatus. Using this approach, we found that heating the membranes at 70–80 K results in a decrease of doublet amplitudes belonging to F X , F A , F B and ferredoxin and simultaneous formation of a new doublet with Δ E Q =3.10 mm/s and δ Fe =1.28 mm/s, typical of inorganic hydrated forms of Fe 2+ . The inhibition of electron transfer via photosystem I to oxygen, catalyzed by ferredoxin, occurs within the same range of temperatures. The data demonstrate that the processes of thermoinduced Fe 2+ formation and distortions in the photosystem I electron transport in the membranes are interrelated and caused mainly by the degradation of ferredoxin. The possible role of Fe 2+ formation in the damage of the photosynthetic apparatus resulting from heating and the action of other extreme factors is discussed.