title: Photosynthetic electron transfer from reaction center pigment-protein complex in silica nanopores.
abstract: A photosynthetic reaction center (RC) pigment-protein complex purified from a thermophilic purple photosynthetic bacterium, Thermochromatium tepidum, was adsorbed to a folded-sheet silica mesoporous material (FSM). The RC has a molecular structure with a 7.0 x 5.0 x 13 nm diameter. The amount of RC adsorbed to the FSM compound with an average internal pore diameter of 7.9 nm (FSM(7.9)) was high at 0.29 gRC/gFSM, while that to the FSM(2.7) (2.7 nm diameter) was low at 0.02 gRC/gFSM, suggesting the specific binding of the RC into the 7.9 nm pores of FSM(7.9). An N(2)-adsorption isotherm study indicated the incorporation of the RC into the 7.9 nm pores. The RC inside FSM(7.9) showed absorption spectra in the visible and infrared regions similar to those of the RC in solution, indicating almost no structural changes induced by the adsorption. The RC-FSM(7.9) conjugate showed the high photochemical activity with the increased thermal stability up to 50 degrees C in the measurements by laser spectroscopy. The conjugates rapidly provided electrons to a dye in the outer medium or showed electric current on the ITO electrode upon the illumination. The RC-FSM conjugate will be useful for the construction of artificial photosynthetic systems and new photodevices.
authors.affiliation: Division of Material Science Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku Nagoya, Aichi 464-8602, Japan.
authors.forename: Ippei
authors.initials: I
authors.lastname: Oda
authors.forename: Masayo
authors.initials: M
authors.lastname: Iwaki
authors.forename: Daiju
authors.initials: D
authors.lastname: Fujita
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Tsutsui
authors.forename: Souji
authors.initials: S
authors.lastname: Ishizaka
authors.forename: Makiko
authors.initials: M
authors.lastname: Dewa
authors.forename: Mamoru
authors.initials: M
authors.lastname: Nango
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kajino
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Fukushima
authors.forename: Shigeru
authors.initials: S
authors.lastname: Itoh
mesh_terms: D004579:Electron Transport; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D010788:Photosynthesis; D011506:Proteins / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011506:Proteins; D012822:Silicon Dioxide