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Selected Publication:

Type of publication: Journal Article
Type of document: Full Paper

Year: 2000

Authors: Pohl, EE; Peterson, U; Sun, J; Pohl, P

Title: Changes of intrinsic membrane potentials induced by flip-flop of long-chain fatty acids.

Source: Biochemistry. 2000; 39(7):1834-1839

Authors Vetmeduni Vienna:

Pohl Elena

The passive transbilayer movement-flip-flop-was investigated on planar bilayer lipid membranes (BLMs), containing myristic, stearic, or linoleic long-chain fatty acids (FA). In response to a transbilayer pH gradient, a difference in the surface charges between inner and outer leaflets appeared. Because the BLM was formed from FA and neutral lipid, a surface potential difference was originated solely by a concentration difference of the initially equally distributed ionized FA. As revealed by zeta-potential measurements, the corresponding surface potential difference DeltaPhi(s) was at least twice the value expected from a titration of the FA alone. The additional surface charge was attributed to FA flip-flop induced by the transbilayer pH gradient. DeltaPhi(s) was derived from capacitive current measurements carried out with a direct current (dc) bias and was corrected for changes of membrane dipole potential Phi(d). Dual-wavelength ratiometric fluorescence measurements have shown that Phi(d) values of the pure DPhPC bilayers and BLMs containing 40 mol % FA differ by less than 6%. It is concluded that fast FA flip-flop is not restricted to membranes with high curvature. The role of pH gradient as an effective driving force for the regulation of FA uptake is discussed.

Keywords Pubmed: Buffers
Fatty Acids/chemistry*
Fatty Acids, Nonesterified/chemistry
Fluorescent Dyes/chemistry
Hydrogen-Ion Concentration
Lipid Bilayers/chemistry*
Membrane Potentials
Pyridinium Compounds/chemistry
Spectrometry, Fluorescence
Stearic Acids/chemistry
Surface Properties

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