title: Fluorescence spectral dynamics of single LHCII trimers.
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.
authors.affiliation: Department of Biophysics, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands. tpj.krueger@few.vu.nl
authors.forename: Tjaart P J
authors.initials: TP
authors.lastname: Krüger
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Novoderezhkin
authors.forename: Cristian
authors.initials: C
authors.lastname: Ilioaia
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism*; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013696:Temperature
chemical_list: D045342:Light-Harvesting Protein Complexes