title: Extension of Light-Harvesting Ability of Photosynthetic Light-Harvesting Complex 2 (LH2) through Ultrafast Energy Transfer from Covalently Attached Artificial Chromophores.
abstract: Introducing appropriate artificial components into natural biological systems could enrich the original functionality. To expand the available wavelength range of photosynthetic bacterial light-harvesting complex 2 (LH2 from Rhodopseudomonas acidophila 10050), artificial fluorescent dye (Alexa Fluor 647: A647) was covalently attached to N- and C-terminal Lys residues in LH2 α-polypeptides with a molar ratio of A647/LH2 ≃ 9/1. Fluorescence and transient absorption spectroscopies revealed that intracomplex energy transfer from A647 to intrinsic chromophores of LH2 (B850) occurs in a multiexponential manner, with time constants varying from 440 fs to 23 ps through direct and B800-mediated indirect pathways. Kinetic analyses suggested that B800 chromophores mediate faster energy transfer, and the mechanism was interpretable in terms of Förster theory. This study demonstrates that a simple attachment of external chromophores with a flexible linkage can enhance the light harvesting activity of LH2 without affecting inherent functions of energy transfer, and can achieve energy transfer in the subpicosecond range. Addition of external chromophores, thus, represents a useful methodology for construction of advanced hybrid light-harvesting systems that afford solar energy in the broad spectrum.
authors.affiliation: Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yoneda
authors.affiliation: Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology , Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.|The OCU Advanced Research Institute for Natural Science & Technology (OCARINA), Osaka City University , 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Noji
authors.affiliation: Institute for NanoScience Design, Osaka University , Toyonaka, Osaka 560-8531, Japan.|PRESTO, Japan Science and Technology Agency (JST) , Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Katayama
authors.affiliation: Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology , Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Mizutani
authors.affiliation: Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology , Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Komori
authors.affiliation: Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology , Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.|The OCU Advanced Research Institute for Natural Science & Technology (OCARINA), Osaka City University , 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Nango
authors.affiliation: Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyasaka
authors.affiliation: Center for Gene Research, Nagoya University , Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Itoh
authors.affiliation: Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.|PRESTO, Japan Science and Technology Agency (JST) , Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nagasawa
authors.affiliation: Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology , Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.|PRESTO, Japan Science and Technology Agency (JST) , Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Takehisa
authors.initials: T
authors.lastname: Dewa
mesh_terms: D000595:Amino Acid Sequence; D031541:Fluorescence Resonance Energy Transfer; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D008969:Molecular Sequence Data; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex