title: Fluorescence intermittency from the main plant light-harvesting complex: sensitivity to the local environment.
abstract: The time-resolved fluorescence intensity fluctuations from single, immobilized complexes of the main light-harvesting complex (LHCII) of plants were investigated in different pH environments close to room temperature and under different light conditions. The efficiency of light harvesting, which was represented by complexes typically residing for long periods in strongly fluorescing states, was significantly reduced by decreasing the pH or increasing the incident photon flux. The same environmental changes significantly increased the switching frequency between strongly and weakly fluorescing states. The environmental dependence became more evident when the various accessed intensity levels were first resolved, a technique that significantly reduced the obscuring effect of shot noise. The strong environmental sensitivity suggests that the immediate environment of an LHCII complex can modulate the amount of energy dissipation. A simple model illustrates how this may be achieved: the dynamic equilibrium between the strongly and weakly fluorescing states can be shifted by environmentally controlling the conformational diffusion on the potential energy surface of LHCII.
authors: Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors: Tjaart P J
authors: TP
authors: Krüger
authors: Cristian
authors: C
authors: Ilioaia
authors: Leonas
authors: L
authors: Valkunas
authors: Rienk
authors: R
authors: van Grondelle
mesh_terms: D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D017785:Photons; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D018724:Spinacia oleracea / Q000201:enzymology
chemical_list: D045342:Light-Harvesting Protein Complexes; D010940:Plant Proteins