title: Protein structural deformation induced lifetime shortening of photosynthetic bacteria light-harvesting complex LH2 excited state.
abstract: Photosynthetic bacterial light-harvesting antenna complex LH2 was immobilized on the surface of TiO(2) nanoparticles in the colloidal solution. The LH2/TiO(2) assembly was investigated by the time-resolved spectroscopic methods. The excited-state lifetimes for carotenoid-containing and carotenoidless LH2 have been measured, showing a decrease in the excited-state lifetime of B850 when LH2 was immobilized on TiO(2). The possibility that the decrease of the LH2 excited-state lifetime being caused by an interfacial electron transfer reaction between B850 and the TiO(2) nanoparticle was precluded experimentally. We proposed that the observed change in the photophysical properties of LH2 when assembled onto TiO(2) nanoparticles is arising from the interfacial-interaction-induced structural deformation of the LH2 complex deviating from an ellipse of less eccentric to a more eccentric ellipse, and the observed phenomenon can be accounted by an elliptical exciton model. Experiment by using photoinactive SiO(2) nanoparticle in place of TiO(2) and core complex LH1 instead of LH2 provide further evidence to the proposed mechanism.
authors.affiliation: Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing.
authors.forename: Xing-Hai
authors.initials: XH
authors.lastname: Chen
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Yu-Xiang
authors.initials: YX
authors.lastname: Weng
authors.forename: Lu-Chao
authors.initials: LC
authors.lastname: Du
authors.forename: Man-Ping
authors.initials: MP
authors.lastname: Ye
authors.forename: Guo-Zhen
authors.initials: GZ
authors.lastname: Yang
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Fujii
authors.forename: Ferdy S
authors.initials: FS
authors.lastname: Rondonuwu
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Koyama
authors.forename: Yi-Shi
authors.initials: YS
authors.lastname: Wu
authors.forename: J P
authors.initials: JP
authors.lastname: Zhang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D055592:Biophysical Phenomena; D001703:Biophysics; D003102:Colloids; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D046912:Multiprotein Complexes; D009154:Mutation; D049329:Nanostructures; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics; D012242:Rhodobacter sphaeroides / Q000737:chemistry / Q000235:genetics; D013053:Spectrophotometry; D014025:Titanium
chemical_list: D001426:Bacterial Proteins; D003102:Colloids; D045342:Light-Harvesting Protein Complexes; D046912:Multiprotein Complexes; D045332:Photosystem II Protein Complex; C009495:titanium dioxide; D014025:Titanium