Abstract
Electrophoretic mobility of cardiolipin liposomes was measured in the presence of polylysines of different molecular weight at various concentrations of the background electrolyte (KCl). The electrophoretic mobility in a liposome suspension changes its sign and reaches a plateau at high polylysine content. The surface charge in the plateau region was determined according to the Gouy-Chapman model of the electrical double layer. The average charge density was found to equal 0.005 and 0.016 Coulomb/m2 for the polymer length of 5 and 12 units (bases), respectively, and 0.032 Coulomb/m2 for polylysines with the length of 130 and 1435 units. The molecular distribution of these polylysines was studied at the mica surface using atomic force microscopy in the 10-mM KCl solution. It was shown that pentalysine molecules covered uniformly about 90% of the surface with the layer thickness of about 0.8 nm. The high-molecular polylysines cover about 60% of the surface with the layer thickness of more than 1.5 nm. The data suggest that the polymer forms a compact layer on the membrane surface; the charge density at the outer surface is determined both by the polymer properties and by the total amount of anionic lipids, irrespective of their ionization state.
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Original Russian Text © O.A. Finogenova, O.V. Batischev, A.V. Indenbom, V.I. Zolotarevsky, Yu.A. Ermakov, 2009, published in Biologicheskie Membrany, 2009, Vol. 26, No. 5, pp. 429–436.
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Finogenova, O.A., Batischev, O.V., Indenbom, A.V. et al. Molecular distribution and charge of polylysine layers at the surface of lipid membranes and mica. Biochem. Moscow Suppl. Ser. A 3, 496–503 (2009). https://doi.org/10.1134/S1990747809040187
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DOI: https://doi.org/10.1134/S1990747809040187