Are "giant" chlorosomes part of light-harvesting antennae of the photosynthetic apparatus in green bacteria?
Borisov, A.I.
Biofizika 54(3): 434-441
2009
ISSN/ISBN: 0006-3029 PMID: 19569502 Document Number: 632326
Some data on the structure and composition of chlorosomes are in contradiction with their energy and kinetic characteristics. Among them is the enormously short excitation lifetime of the dominating chlorosoma pigment C740 in three-dimensional giant chlorosoma (with about 1000 pigment molecules per reaction center). With these times, it is hardly possible to obtain an efficient excitation transfer from this pigment to the bacteriochlorophyll B795 of the base plate and further to the main bacteriochlorophyll B860, which directly serves as reaction centers. This result was obtained by modeling the energy migration between these pigment fractions in maximally optimized conditions. Possible reasons and mechanisms responsible for such a strong nonphotochemical quenching of electronic excitations in the pigments of giant chlorosomes are substantiated and discussed.