The local electric field within phospholipid membranes modulates the charge transfer reactions in reaction centres

Anne Pilotelle-Bunner, Patricia Beaunier, Julia Tandori, P. Maróti, Ronald J. Clarke, Pierre Sebban

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Three different cholesterol derivatives and phloretin, known to affect the local electric field in phospholipid membranes, have been introduced into Rhodobacter sphaeroides reaction centre-containing phospholipid liposomes. We show that cholesterol and 6-ketocholestanol significantly slow down the interquinone first electron transfer (∼ 10 times), whereas phloretin and 5-cholesten-3β-ol-7-one leave the kinetics essentially unchanged. Interestingly, the two former compounds have been shown to increase the dipole potential, whereas the two latter decrease it. We also measured in isolated RCs the rates of the electron and proton transfers at the first flash. Over the pH range 7-10.5 both reactions display biphasic behaviors with nearly superimposable rates and amplitudes, suggesting that the gating process limiting the first electron transfer is indeed the coupled proton entry. We therefore interpret the effects of cholesterol and 6-ketocholestanol as due to dipole concentration producing an increased free energy barrier for protons to enter the protein perpendicular to the membrane. We also report for the first time in R. sphaeroides RCs, at room temperature, a biphasicity of the P+QA- charge recombination, induced by the presence of cholesterol derivatives in proteoliposomes. We propose that these molecules decrease the equilibration time between two RC conformations, therefore revealing their presence.

Original languageEnglish
Pages (from-to)1039-1049
Number of pages11
JournalBBA - Bioenergetics
Volume1787
Issue number8
DOIs
Publication statusPublished - Aug 2009

Fingerprint

Charge transfer
Phospholipids
Cholesterol
Electric fields
Phloretin
Membranes
Protons
Rhodobacter sphaeroides
Electrons
Derivatives
Proton transfer
Energy barriers
Liposomes
Genetic Recombination
Free energy
Conformations
Molecules
Kinetics
Temperature
Proteins

Keywords

  • Biological membrane
  • Cholesterol
  • Dipole potential
  • Electron transfer
  • Proton transfer
  • Reaction centre protein

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology

Cite this

The local electric field within phospholipid membranes modulates the charge transfer reactions in reaction centres. / Pilotelle-Bunner, Anne; Beaunier, Patricia; Tandori, Julia; Maróti, P.; Clarke, Ronald J.; Sebban, Pierre.

In: BBA - Bioenergetics, Vol. 1787, No. 8, 08.2009, p. 1039-1049.

Research output: Contribution to journalArticle

Pilotelle-Bunner, Anne ; Beaunier, Patricia ; Tandori, Julia ; Maróti, P. ; Clarke, Ronald J. ; Sebban, Pierre. / The local electric field within phospholipid membranes modulates the charge transfer reactions in reaction centres. In: BBA - Bioenergetics. 2009 ; Vol. 1787, No. 8. pp. 1039-1049.
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