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Updated: Aug 10, 2026
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Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Pathways of proton transfer in the light-driven pump bacteriorhodopsin
1Department of Physiology and Biophysics, University of California, Irvine 92717.
Experientia
|July 5, 1993
Summary
Bacteriorhodopsin uses light to pump protons across membranes. Light triggers retinal isomerization, sequentially altering proton binding sites to move protons from the cytoplasm to the outside.
Area of Science:
- Biochemistry
- Biophysics
- Structural Biology
Background:
- Bacteriorhodopsin is a light-driven proton pump.
- Understanding its proton transport mechanism is crucial.
Purpose of the Study:
- To elucidate the mechanism of proton transport in bacteriorhodopsin.
- To detail the sequence of events following light activation.
Main Methods:
- The study focuses on the photoreaction cycle of bacteriorhodopsin.
- It examines the transient changes in pKa values of key amino acid residues.
Main Results:
- Light induces all-trans to 13-cis isomerization of the retinal chromophore.
- This isomerization leads to sequential pKa decreases in the retinal Schiff base, extracellular (asp-85), and cytoplasmic (asp-96) proton complexes.
- The precisely timed pKa changes drive sequential proton transfers.
Conclusions:
- The sequential pKa shifts facilitate directed proton movement across the protein.
- This mechanism results in net proton translocation from the cytoplasmic to the extracellular side.
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