MIHAELA BACALUM*, M. RADU**
*Department of Biophysics, Faculty of Physics, University of Bucharest, Măgurele, Romania
**Department of Health and Environmental Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, PO Box MG6, Măgurele, 077125, Romania
Abstract. Many processes at the level of biological membranes involve the participation of integral and/or adsorbed proteins. The proper functioning of the membrane proteins is related to the local molecular environment, one of the most important factors being the lipid bilayer. In this paper we present a method to evidence the interaction of proteins with the lipid bilayer in artificial lipid membranes using the fluorescence resonance energy transfer (FRET) method. The donor in the energy transfer process is the tryptophan residue from the proteins and the acceptor is diphenylhexatriene, a lipid bilayer fluorescencent marker. Liposomes prepared from lecitine and synthetic lipids were used as model membranes. The FRET procedure was first tested on gramicidin A inserted in the liposome bilayer and afterwards applied to study the insertion of a bacterial outer membrane porin, namely OmpF. Recording the spectra of liposomes-protein-diphenylhexatriene complex for different concentration of the acceptor, the energy transfer was evidenced and the results were discussed in the terms of FRET efficiency.
Key words: protein insertion, liposomes, fret, gramicidin, OmpF
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