title: Carotenoid triplet states associated with the long-wavelength-emitting chlorophyll forms of photosystem I in isolated thylakoid membranes.
abstract: The carotenoid triplet populations associated with the long-wavelength-emitting chlorophyll forms of photosystem I (PS I)(dagger) have been investigated in isolated spinach thylakoids by means of fluorescence-detected magnetic resonance in zero field. The spectra collected in the 730-800 nm emission range can be globally fitted assuming the presence of four different carotenoid triplet states coupled to long-wavelength-emitting forms of PS I, having zero-field-splitting parameters /D/ = 0.0359 cm(-1) and /E/ = 0.00371 cm(-1), /D/ = 0.0382 cm(-1) and /E/ = 0.00388 cm(-1), /D/ = 0.0395 cm(-1) and /E/ = 0.00397 cm(-1), and /D/ = 0.0405 cm(-1) and /E/ = 0.00411 cm(-1). On the basis of the triplet-associated fluorescence emission profile, it is suggested that those triplets are associated with light-harvesting complex I, the peripheral antenna complex of PS I.
authors.affiliation: School of Biological Sciences, Queen Mary University of London, Mile End Road, E1 4NS London, United Kingdom. s.santabarbara@qmul.ac.uk
authors.forename: Stefano
authors.initials: S
authors.lastname: Santabarbara
authors.forename: Donatella
authors.initials: D
authors.lastname: Carbonera
mesh_terms: D002338:Carotenoids / Q000737:chemistry*; D002734:Chlorophyll / Q000737:chemistry*; D007425:Intracellular Membranes / Q000737:chemistry*; D045331:Photosystem I Protein Complex / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D018724:Spinacia oleracea / Q000737:chemistry; D020524:Thylakoids / Q000737:chemistry*
chemical_list: D045331:Photosystem I Protein Complex; D002734:Chlorophyll; D002338:Carotenoids