Effect of low temperatures on photochemical activity of PS1 reaction centers from Synechocystis sp. frozen under illumination
After cooling of Synechocystis sp. photosystem 1 (PS1) reaction centers (RC) to 160 K under illumination most of the photoactive pigment is fixed for a long time in the oxidized state. The same effect is observed in purple bacteria RC. The dark reduction kinetics of PS1 P700 chlorophyll, which still...
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Published in | Biochemistry (Moscow) Vol. 69; no. 12; pp. 1399 - 1402 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
Springer
01.12.2004
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Subjects | |
Online Access | Get full text |
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Summary: | After cooling of Synechocystis sp. photosystem 1 (PS1) reaction centers (RC) to 160 K under illumination most of the photoactive pigment is fixed for a long time in the oxidized state. The same effect is observed in purple bacteria RC. The dark reduction kinetics of PS1 P700 chlorophyll, which still retains its photochemical activity, in these samples was similar to that in samples cooled in the dark. We suggest that the photoinduced charge separation in PS1 RC, as well as in purple bacteria RC, is accompanied by conformational changes that can be fixed in samples cooled under illumination. As a result, the electrons photomobilized in RC cooled under illumination are unable to return backward the process of electron transfer to P700(+) after cessation of actinic illumination. Such irreversible trapping of electrons can take place in different parts of the PS1 RC electron acceptor chain. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0006-2979 1608-3040 0320-9725 |
DOI: | 10.1007/s10541-005-0087-2 |