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Updated: Jun 19, 2026
10:03
Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Bacteriorhodopsin O-state photocycle kinetics: a surfactant study
Li-Kang Chu1, Mostafa A El-Sayed
1Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA.
Photochemistry and Photobiology
|October 23, 2009
Summary
Bacteriorhodopsin
Area of Science:
- Biophysics
- Spectroscopy
- Membrane Proteins
Background:
- Bacteriorhodopsin (bR) is a light-driven proton pump.
- Understanding bR's functional states is crucial for bioenergetics.
- Surfactants can modulate protein structure and function.
Purpose of the Study:
- Investigate the effects of various surfactants on the O intermediate of bacteriorhodopsin.
- Determine how different surfactant types influence bR's spectroscopic and dynamic properties.
- Assess the impact on proton pumping efficiency.
Main Methods:
- Steady-state UV-VIS spectrometry
- Circular dichroism (CD) spectroscopy
- Time-resolved absorption spectroscopy
Main Results:
- Bacteriorhodopsin retains its trimeric structure with nonionic C6E2 up to a high molar ratio.
- Nonionic C6E2 increases the rise and decay rates and transient populations of the O state.
- Ionic surfactants (CTAB, SDS) show opposite effects on the O state dynamics.
- C6E2 treatment enhances the O intermediate population by 40%, suggesting improved proton pumping.
Conclusions:
- Nonionic surfactant C6E2 stabilizes bR structure and enhances proton pumping efficiency.
- Ionic surfactants CTAB and SDS negatively impact bR's O state dynamics.
- Structural expansion induced by C6E2 is linked to increased proton pumping efficiency.
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