B. AMUZESCU*, S. ION**, D. POPESCU**, L. MOVILEANU***, SPERANŢA AVRAM*, BEATRICE MACRI*, MARIA-LUISA FLONTA*

*Dept. Biophysics & Physiology, Faculty of Biology, University of Bucharest, Splaiul Independenţei 91–96, Bucharest R-76201, Romania
**Institute of Applied Mathematics, Calea 13 Septembric 13, P.O.Box 1-24, Bucharest, Romania
***Dept. Medical Biochemistry & Genetics, The Texas A&M University System Health Science Center, 440 Reynolds Medical Building, College Station, Texas 77843-1114, USA

Abstract. Within the present work we determined the conditions for transbilayer pore formation due to thermal group motion of phospholipid bilayer molecules. The radius of the area containing molecules that move almost simultaneously perpendicular to the bilayer surface is within the range [Rmin, Rmax]. Bilayer deformation is characterized by its wavelength, which is also confined to a limited and continuous range. The limits of both R and the wavelength depend on the thickness of the bilayer’s hydrophobic core, on temperature, polar group size, surface tension and on the hilayer’s elastic properties (elastic compression and splay). The conditions for transbilayer pore formation depend quantitatively on the radius of the perturbation area and on the bilayer deformation wavelength.

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