The Study of the Interaction of a Model α-Helical Peptide with Lipid Bilayers and Monolayers

P. Vitovic 1R.N.A.H. Lewis 2R.N. McElhaney 2Tibor Hianik 1

1. Comenius University, Department of Biophysics and Chemical Physics, Mlynská dolina F1, Bratislava 842 48, Slovakia (Slovak Rep.)
2. University of Alberta, Department of Biochemistry, Edmonton T6G 2H7, Canada

Abstract

We studied the interaction of the α-helical peptide acetyl-Lys2-Leu24-Lys2-amide (L24) with tethered bilayer lipid membranes (tBLM) and lipid monolayers formed at an air-water interface. The interaction of L24 with tBLM resulted in strong adsorption of the peptide to the surface of the bilayer, characterized by a binding constant of 40±8 nM-1. This binding constant was similar to that characteristic of the specific interaction of some hormonal peptides with their receptors. The peptide an induced increase in the compressibility of the tBLM in a direction perpendicular to the membrane surface. The pure peptide formed a stable monolayer at the air/water interface. The pressure-area isotherms were characterized by a transition of the peptide monolayer, which probably corresponds of the partial intercalation of the α-helixes at higher surface pressure. Interaction of the peptide molecules with lipid monolayers resulted in an increase of the mean molecular area of phospholipids both in the gel and liquid-crystalline states. With increasing peptide concentration, the temperature of the phase transition of the monolayer shifted toward lower temperatures. The analysis showed that the peptide-lipid monolayer is not an ideally miscible system and that the peptide molecules form aggregates in the monolayer.

 

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Presentation: Short communication at SMCBS 2003 Workshop, by P. Vitovic
See On-line Journal of SMCBS 2003 Workshop

Submitted: 2003-10-03 20:46
Revised:   2009-06-08 12:55