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. 1988 Dec;85(24):9509–9513. doi: 10.1073/pnas.85.24.9509

Monomeric and aggregated bacteriorhodopsin: Single-turnover proton transport stoichiometry and photochemistry

Stephan Grzesiek 1, Norbert A Dencher 1
PMCID: PMC282783  PMID: 16594006

Abstract

The question of the basic functional transport unit of bacteriorhodopsin (BR) has been addressed by comparing the proton pumping stoichiometry as well as the photocycle kinetics of monomeric and aggregated BR in phospholipid vesicles. When time-resolved laser spectroscopy was used in combination with the optical pH-indicator pyranine, single-turnover experiments revealed approximately 0.5-0.8 and 0.8-1.2 protons vectorially translocated per photocycling monomeric and aggregated BR molecule, respectively. Since both these values are akin and very similar to the pumping stoichiometry of crystalline BR molecules in the purple membrane, the BR monomer has been proven to be the essential transport unit. The natural arrangement of the photopigments in a crystalline array of immobilized trimers is not required for efficient vectorial proton translocation.

Keywords: bacteriorhodopsin, reconstituted vesicles, proton pumping, flash spectroscopy, pH indicator

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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