• antimicrobial peptide
• membrane
• solid state NMR

This thesis work concerns the study of the interactions between the synthetic antimicrobial peptide (YI13C)2 and model cell membranes by Solid State Nuclear Magnetic Resonance (SSNMR) techniques.
The strategy used for the study involved the preparation of POPC ( 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) model cell membranes and the application of a multi-nuclear and multi-technique solid state NMR approach to study the interactions between the components of the system at a molecular level. Both non aligned and mechanically aligned samples were prepared and studied. The observation of the nuclei 31P, 2H, 1H and the measurement of different spectral properties gave structural and dynamic information on both the polar region of the bilayers and the water contained in the phase.
From the study of non aligned samples a perturbative effect of the peptide on the bilayer structure and on the dynamic properties of water molecules was shown. The dependence of the perturbation on the concentration of the peptide and on the hydration of the membranes was revealed. The exploitation of mechanical alignment gave further information on the perturbation mechanism.
From a compared analysis of all the experimental results some hints on the model of action of the peptide in the system studied were obtained.
In addition, the properties of differently purified samples of LPS (lipopolysaccharide) in aqueous environment were preliminarily studied by 31P SSNMR.