We have found that, at low light intensity (5–10 μmol photons·m−2·s−1), photoreduction of cyt (cytochrome) c by isolated thylakoids was not inhibited by dinitrophenylether of iodonitrothymol, an inhibitor of the cyt b6–f complex, and the inhibition was only partial at medium light intensity (50–200 μmol photons·m−2·s−1). The photoreduction was not significantly influenced by superoxide dismutase. The conclusion that cyt c could be reduced directly by the plastoquinone pool was confirmed by the observation that plastoquinol-9 reduced cyt c efficiently when it was incorporated into liposome membranes prepared from thylakoid membrane lipids. It was shown that the cyt is specifically bound to thylakoid lipid liposomes owing to the presence of negatively charged lipids, phosphatidylglycerol and sulphoquinovosyldiacylglycerol, and the reduction was stimulated by the presence of monogalactosyldiacylglycerol, an inverted micelles-forming lipid, in the membranes, where the cyt c reduction by plastoquinol probably takes place. The results obtained are also discussed in terms of reliability of the method of cyt c photoreduction for determining superoxide production by illuminated thylakoids.
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October 2003
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Research Article|
October 01 2003
Cytochrome c is reduced mainly by plastoquinol and not by superoxide in thylakoid membranes at low and medium light intensities: its specific interaction with thylakoid membrane lipids
Jerzy KRUK;
Jerzy KRUK
1
Department of Plant Physiology and Biochemistry, Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
1To whom correspondence should be addressed (e-mail jkruk@mol.uj.edu.pl).
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Małgorzata JEMIOŁA-RZEMIŃSKA;
Małgorzata JEMIOŁA-RZEMIŃSKA
Department of Plant Physiology and Biochemistry, Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
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Kazimierz STRZAŁKA
Kazimierz STRZAŁKA
Department of Plant Physiology and Biochemistry, Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
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Publisher: Portland Press Ltd
Received:
November 21 2002
Revision Received:
June 18 2003
Accepted:
July 01 2003
Accepted Manuscript online:
July 01 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2003
2003
Biochem J (2003) 375 (1): 215–220.
Article history
Received:
November 21 2002
Revision Received:
June 18 2003
Accepted:
July 01 2003
Accepted Manuscript online:
July 01 2003
Citation
Jerzy KRUK, Małgorzata JEMIOŁA-RZEMIŃSKA, Kazimierz STRZAŁKA; Cytochrome c is reduced mainly by plastoquinol and not by superoxide in thylakoid membranes at low and medium light intensities: its specific interaction with thylakoid membrane lipids. Biochem J 1 October 2003; 375 (1): 215–220. doi: https://doi.org/10.1042/bj20021820
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