title: Two wavelength-dependent mechanisms of sensitisation of light-induced quenching in the isolated light-harvesting complex II.
abstract: The efficiency of visible light in inducing fluorescence quenching in the isolated light-harvesting complex II (LHCII) of higher plants is investigated by action spectroscopy in the visible portion of photosynthetic active radiation. The efficiency spectrum displays a relatively homogenous quenching yield across the most intense electronic transitions of the chlorophyll a and carotenoid pigments, indicating that quenching proceeds from the equilibrated state of the complex. Larger yields are observed in the 510-640-nm window, where weak transitions of LHCII-bound chromophores occur. This observation is interpreted in terms of an additional quenching sensitisation process mediated by these electronic transitions.
authors.affiliation: Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Milano, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Santabarbara
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, Lublin, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Zubik
authors.affiliation: Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Milano, Italy.
authors.forename: William
authors.initials: W
authors.lastname: Remelli
authors.affiliation: Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zucchelli
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, Lublin, Poland.
authors.forename: Wieslaw I
authors.initials: WI
authors.lastname: Gruszecki
mesh_terms: D002338:Carotenoids / Q000096:biosynthesis / Q000235:genetics; D002734:Chlorophyll / Q000235:genetics / Q000378:metabolism*; D000077194:Chlorophyll A; D004579:Electron Transport / Q000235:genetics; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000235:genetics* / Q000302:isolation & purification; D010788:Photosynthesis / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000235:genetics*; D018724:Spinacia oleracea / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D002338:Carotenoids; D000077194:Chlorophyll A
keywords: action spectra; light-harvesting complex; light-induced quenching; nonphotochemical quenching; quantum efficiency