Light induced transmembrane proton gradient in artificial lipid vesicles reconstituted with photosynthetic reaction centers

Francesco Milano, Massimo Trotta, Márta Dorogi, Béla Fischer, Livia Giotta, Angela Agostiano, Péter Maróti, László Kálmán, László Nagy

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Photosynthetic reaction center (RC) is the minimal nanoscopic photoconverter in the photosynthetic membrane that catalyzes the conversion of solar light to energy readily usable for the metabolism of the living organisms. After electronic excitation the energy of light is converted into chemical potential by the generation of a charge separated state accompanied by intraprotein and ultimately transmembrane proton movements. We designed a system which fulfills the minimum structural and functional requirements to investigate the physico/chemical conditions of the processes: RCs were reconstituted in closed lipid vesicles made of selected lipids entrapping a pH sensitive indicator, and electron donors (cytochrome c2 and K 4[Fe(CN)6]) and acceptors (decylubiquinone) were added to sustain the photocycle. Thanks to the low proton permeability of our preparations, we could show the formation of a transmembrane proton gradient under illumination and low buffering conditions directly by measuring proton-related signals simultaneously inside and outside the vesicles. The effect of selected ionophores such as gramicidin, nigericin and valinomycin was used to gain more information on the transmembrane proton gradient driven by the RC photochemistry.

Original languageEnglish
Pages (from-to)373-384
Number of pages12
JournalJournal of Bioenergetics and Biomembranes
Volume44
Issue number3
DOIs
Publication statusPublished - Jun 1 2012

Keywords

  • Ionophores
  • Proton motive force
  • Pyranine
  • Reaction centers

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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