Reaction Dynamics of Halorhodopsin Studied by Time-Resolved Diffusion
AUTOR(ES)
Inoue, Keiichi
FONTE
The Biophysical Society
RESUMO
Reaction dynamics of a chloride ion pump protein, halorhodopsin (HR), from Natronomonas pharaonis (N. pharaonis) (NpHR) was studied by the pulsed-laser-induced transient grating (TG) method. A detailed investigation of the TG signal revealed that there is a spectrally silent diffusion process besides the absorption-observable reaction dynamics. We interpreted these dynamics in terms of release, diffusion, and uptake of the Cl− ion. From a quantitative global analysis of the signals at various grating wavenumbers, it was concluded that the release of the Cl− ion is associated with the L2 → (L2 (or N) ⇆ O) process, and uptake of Cl− occurs with the (L2 (or N) ⇆ O) → NpHR′ process. The diffusion coefficient of NpHR solubilized in a detergent did not change during the cyclic reaction. This result contrasts the behavior of many photosensor proteins and implies that the change in the H-bond network from intra- to intermolecular is not significant for the activity of this protein pump.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2711408Documentos Relacionados
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