Open Access

Membrane potential-dependent binding of polysialic acid to lipid monolayers and bilayers

  • Krzysztof Nowotarski1,
  • Karolina Sapoń1,
  • Monika Kowalska1,
  • Tadeusz Janas1 and
  • Teresa Janas1Email author
Cellular & Molecular Biology LettersAn International Journal201318:108

https://doi.org/10.2478/s11658-013-0108-x

Received: 2 June 2013

Accepted: 25 November 2013

Published: 30 November 2013

Abstract

Polysialic acids are linear polysaccharides composed of sialic acid monomers. These polyanionic chains are usually membrane-bound, and are expressed on the surfaces of neural, tumor and neuroinvasive bacterial cells. We used toluidine blue spectroscopy, the Langmuir monolayer technique and fluorescence spectroscopy to study the effects of membrane surface potential and transmembrane potential on the binding of polysialic acids to lipid bilayers and monolayers. Polysialic acid free in solution was added to the bathing solution to assess the metachromatic shift in the absorption spectra of toluidine blue, the temperature dependence of the fluorescence anisotropy of DPH in liposomes, the limiting molecular area in lipid monolayers, and the fluorescence spectroscopy of oxonol V in liposomes. Our results show that both a positive surface potential and a positive transmembrane potential inside the vesicles can facilitate the binding of polysialic acid chains to model lipid membranes. These observations suggest that these membrane potentials can also affect the polysialic acid-mediated interaction between cells.

Key words

Polysialic acidPolyanionLipid bilayerLipid monolayerMembrane potentialLiposomeDPH anisotropy

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