Biological and model membranes studied by nuclear magnetic resonance of spin one half nuclei

Abstract

There is an inherent anisotropy in biological and model membrane systems and this anisotropy has a profound influence on the nuclear magnetic resonance spectra of such systems. For nuclei with a quadrupole moment the quadrupole coupling usually dominates the NMR spectrum, while for nuclei with spin quantum numberI= ½ dipolar couplings provides the most important effects. The quadrupole coupling only affects isolated spins and usually gives rise to simple spectra. The dipole interactions on the other hand couple several spins. In a lipid bilayer with a multitude of spin-½ nuclei these couplings can give rise to complicated manybody effects. Thus the interpretation of the NMR spectra of membrane systems poses problems but at the same time there is a lot of information to be gained.