NUKLEONIKA 2013, 58(3):443-446

 


THE INFLUENCE OF SELECTED AMINO ACIDS ON THE DYNAMIC PROPERTIES OF THE LIPOSOME MEMBRANES: ESR STUDY



Dariusz Man1, Małgorzata Broda2, Aneta Buczek2, Anna Kawecka3, Dawid Siodłak2

1 Institute of Physics, Opole University, 48 Oleska Str., 45-052 Opole, Poland
2 Faculty of Chemistry, Opole University, 48 Oleska Str., 45-052 Opole, Poland
3 T. Koszarowski Oncology Center in Opole, 66a Katowicka Str., Opole, Poland

In this work the changes in the fluidity of liposome membranes caused by alanine and butyrine derivatives (Ac-Ala-NMe2 and Ac-Abu-NMe2) were investigated. Liposomes were obtained in the process of egg yolk lecithin (EYL) sonication. The concentration of the admixture in the proportion to EYL varied from 0 to 25% mole. The electron spin resonance (ESR) spectroscopy was used with two different spins probes. Each spin probe penetrates different regions of liposome membrane. The TEMPO probe occurs both in the hydrophobic part of the membrane and in the water environment what allows to determine the spectroscopic parameter F of division of this probe into the membrane and its water surrounding. DOXYL is localized in the central part of the lipid bilayer and is used to obtain the spectroscopic parameter #tau# – rotation correlation time – whose value gives information about fluidity changes in the middle of the lipid bilayer. The study indicated that the tested as admixtures N-methylated model peptides significantly changed the fluidity of liposome membranes. The dynamic of this process depends both on amino acids derivative and on the membrane region. Both studied compounds increased the fluidity of the surface layer of liposome membrane. At the same time, butyrine derivative caused the stiffening of the middle part of liposome bilayer, but alanine derivative slightly increased the fluidity of this region.

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