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.
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.
Oikawa
Hiroyuki
H
Department of Physics, Tokyo Institute of Technology, Meguro 152-8551, Japan.
Fujiyoshi
Satoru
S
Dewa
Takehisa
T
Nango
Mamoru
M
Matsushita
Michio
M
D001426:Bacterial Proteins / Q000737:chemistry*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D011487:Protein Conformation; D012241:Rhodopseudomonas / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; C026083:bacteriochlorophyll A proteins, Bacteria