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Biophys J. 2010 Jun 16;98(12):3093-101. doi: 10.1016/j.bpj.2010.03.028.

Fluorescence spectral dynamics of single LHCII trimers.

Author information

1
Department of Biophysics, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands. tpj.krueger@few.vu.nl

Abstract

Single-molecule spectroscopy was employed to elucidate the fluorescence spectral heterogeneity and dynamics of individual, immobilized trimeric complexes of the main light-harvesting complex of plants in solution near room temperature. Rapid reversible spectral shifts between various emitting states, each of which was quasi-stable for seconds to tens of seconds, were observed for a fraction of the complexes. Most deviating states were characterized by the appearance of an additional, red-shifted emission band. Reversible shifts of up to 75 nm were detected. By combining modified Redfield theory with a disordered exciton model, fluorescence spectra with peaks between 670 nm and 705 nm could be explained by changes in the realization of the static disorder of the pigment-site energies. Spectral bands beyond this wavelength window suggest the presence of special protein conformations. We attribute the large red shifts to the mixing of an excitonic state with a charge-transfer state in two or more strongly coupled chlorophylls. Spectral bluing is explained by the formation of an energy trap before excitation energy equilibration is completed.

PMID:
20550923
PMCID:
PMC2884258
DOI:
10.1016/j.bpj.2010.03.028
[Indexed for MEDLINE]
Free PMC Article

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