Pathways of proton transfer in the light-driven pump bacteriorhodopsin |
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Authors: | Lanyi J K |
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Institution: | Department of Physiology and Biophysics, University of California, Irvine 92717. |
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Abstract: | The mechanism of proton transport in the light-driven pump bacteriorhodopsin is beginning to be understood. Light causes the all-trans to 13-cis isomerization of the retinal chromophore. This sets off a sequential and directed series of transient decreases in the pKa's of a) the retinal Schiff base, b) an extracellular proton release complex which includes asp-85, and c) a cytoplasmic proton uptake complex which includes asp-96. The timing of these pKa changes during the photoreaction cycle causes sequential proton transfers which result in the net movement of a proton across the protein, from the cytoplasmic to the extracellular surface. |
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