Microstructural characterization of phospholipid membranes and study of their interaction with peptides and proteins.
Vitiello, Giuseppe (2011) Microstructural characterization of phospholipid membranes and study of their interaction with peptides and proteins. [Tesi di dottorato] (Inedito)
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In the present thesis, a wide structural and functional study on biomembranes is presented. The research has been focused on the micro- and mesostructure of phospholipid bilayers and on their interactions with different peptides which are involved in important biological process. Particularly, the role of lipid composition and self-organization in regulating the membrane biophysical properties has been investigated. In particular, the experimental study is aimed to contribute to the analysis of the fine interplay between lipids and proteins/peptides in regulating processes involving biomembranes. The experimental work has been divided in two parts. In the former one, the attention has been focused on the formulation and the contemporary physico-chemical characterization of biomimicking lipid systems, as liposomes and supported lipid bilayers. Different classes of lipids were considered, incluiding zwitterionic and anionic, mono- and bichained, mono-, bi- and polyunsaturated phospholipids. Cholesterol and sphingolipids were also used in order to discriminate the effect of lipid composition in modulating the microstructural properties of lipid bilayers and their mesoscopic organization. In the latter part of the research, the interaction of these lipid systems with peptides deriving from different viral glycoproteins as well as from the A peptide was analyzed. The whole investigation was realized by a combined experimental approach in which many physico-chemical techniques were used in order to obtain a wide description of the systems structure and behavior. In particular, Electron Spin Resonance (ESR) spectroscopy and Neutron Reflectivity (NR) have provided information about the lipid ordering and dynamics in the bilayer, while spectrofluorimetry and circular dichroism (CD) measurements have allowed the direct monitoring of the peptides behavior in the presence of membrane environment. Finally, Dynamic Light Scattering (DLS) and Small Angle Neutron Scattering (SANS) experiments have permitted a mesoscopic analysis of the different lipid supramolecular aggregates.
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