title: Chlorophyll triplet quenching by fucoxanthin in the fucoxanthin-chlorophyll protein from the diatom Cyclotella meneghiniana.
abstract: In this work we present an optically detected magnetic resonance (ODMR) study on the triplet states populated under illumination in the isolated fucoxanthin-chlorophyll light-harvesting complex from the diatom Cyclotella meneghiniana. Evidence for the quenching of chlorophyll triplet states by fucoxanthin is provided, showing that this carotenoid is able to perform the photoprotective role. For the first time, the magnetic parameters characterizing the fucoxanthin triplet state have been determined. The results reveal analogies but also differences with respect to the triplet-triplet energy transfer process, which involves chlorophylls a and carotenoids in the LHC complex from dinoflagellates and LHCII from higher plants. The degree of efficiency of the photoprotection mechanism, in these light harvesting complexes, is discussed in terms of pigment-protein structure.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padova, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Di Valentin
authors.forename: Claudia
authors.initials: C
authors.lastname: Büchel
authors.forename: Giorgio Mario
authors.initials: GM
authors.lastname: Giacometti
authors.forename: Donatella
authors.initials: D
authors.lastname: Carbonera
mesh_terms: D002734:Chlorophyll / Q000737:chemistry*; D061146:Chlorophyll Binding Proteins / Q000737:chemistry*; D017377:Diatoms / Q000201:enzymology*; D005453:Fluorescence; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D024341:Xanthophylls / Q000737:chemistry*
chemical_list: D061146:Chlorophyll Binding Proteins; D024341:Xanthophylls; C025164:fucoxanthin; D002734:Chlorophyll