title: Ultrafast excitation relaxation dynamics of lutein in solution and in the light-harvesting complexes II isolated from Arabidopsis thaliana.
abstract: Ultrafast excitation relaxation dynamics and energy-transfer processes in the light-harvesting complex II (LHC II) of Arabidopsis thaliana were examined at physiological temperature using femtosecond time-resolved fluorescence spectroscopy. Energy transfer from lutein to Chl a proceeded with a rate constant of k(ET) = 1.8-1.9 x 10(13) s(-1) and a yield of approximately Phi(ET) = 0.70, whereas that from neoxanthin to Chl a had a rate constant of k(ET) = 6.5 x 10(11) s(-1) and a yield at the most of Phi(ET) = 0.09. Fluorescence anisotropic decay of lutein in LHC II showed a value larger than 0.4 at the initial state and decayed to approximately 0.1 in 0.3 ps, indicating that two lutein molecules interact with each other in LHC II. In solution, anisotropy of lutein remained constant (0.38) independent of time, and thus a new excited state inferred between the S(2) (1B(u)) state and the S(1) (2A(g)) state was not applicable for lutein in solution. Energy migration processes among Chl a or Chl b molecules were clearly resolved by kinetic analysis. On the basis of these results, relaxation processes and energy-transfer kinetics in LHC II of A. thaliana are discussed.
authors.affiliation: Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan. akimoto@eng.hokudai.ac.jp
authors.forename: Seiji
authors.initials: S
authors.lastname: Akimoto
authors.forename: Makio
authors.initials: M
authors.lastname: Yokono
authors.forename: Maiko
authors.initials: M
authors.lastname: Ohmae
authors.forename: Iwao
authors.initials: I
authors.lastname: Yamazaki
authors.forename: Ayumi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Michiya
authors.initials: M
authors.lastname: Higuchi
authors.forename: Tohru
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyashita
authors.forename: Mamoru
authors.initials: M
authors.lastname: Mimuro
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes / Q000302:isolation & purification* / Q000378:metabolism*; D014975:Lutein / Q000737:chemistry* / Q000378:metabolism*; D015394:Molecular Structure; D012996:Solutions / Q000737:chemistry; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D045342:Light-Harvesting Protein Complexes; D012996:Solutions; D014975:Lutein