title: How deep is the potential well confining a protein in a specific conformation? A single-molecule study on temperature dependence of conformational change between 5 and 18 K.
abstract: The fluorescence excitation spectrum of a single chromophore molecule in a photosynthetic pigment-protein complex is known to change in time at liquid helium temperature. The spectral change reflects a conformational change of the protein to which the chromophore binds. This work follows the temporal behavior of the spectrum of a single chromophore in the temperature range between 5 adn 18 K. The temperature dependence reveals two types of conformational change of the protein, i.e., thermally activated motions over a potential barrier of ca. 0.1 kJ/mol and temperature-independent motions of tunneling of a proton.
authors.affiliation: Department of Physics, Tokyo Institute of Technology, Meguro 152-8551, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oikawa
authors.forename: Satoru
authors.initials: S
authors.lastname: Fujiyoshi
authors.forename: Takehisa
authors.initials: T
authors.lastname: Dewa
authors.forename: Mamoru
authors.initials: M
authors.lastname: Nango
authors.forename: Michio
authors.initials: M
authors.lastname: Matsushita
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D011487:Protein Conformation; D012241:Rhodopseudomonas / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; C026083:bacteriochlorophyll A proteins, Bacteria