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Andrei G. Yakovlev, Alexandra S. Taisova, Zoya G. Fetisova
Intramolecular
femtosecond conversion of energy in the chlorosomes of photosynthetic green
bacteria Chloroflexus Aurantiacus
Abstract
Abstract. In the
green bacteria Chloroflexus aurantiacus, the process of photosynthesis
begins with the absorption of light by unique light-harvesting complexes,
chlorosomes, which consist of ~104 bacteriochlorophyll (BChl) c
molecules combined into complex spatial structures. Upon absorption of blue light (~460 nm) by the B band of
chlorosomes, ultrafast energy conversion occurs, resulting in the excitation of
the red Qy band (~740 nm).We studied this process using difference
(light-dark) absorption spectroscopy with a high time resolution (20 fs). We have found that the characteristic conversion time is 35 fs. We have
shown that energy conversion precedes slower processes of exciton relaxation in
the Qy band (100–300 fs) and energy transfer from the
chlorosome to the baseplate and further to the reaction center (tens of ps).The
physicochemical foundations of intramolecular energy conversion in chlorosomes
and the significance of this process for photosynthesis are discussed.
Key words: photosynthesis, chlorosome, bacteriochlorophyll, energy conversion,
femtosecond spectroscopy
Copyright (C) Chemistry Dept., Moscow State University, 2002
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