A novel approach to the study of mammalian cell‐membranes using deuterium NMR

Several recent studies using different physical techniques [ 1,2] indicate that the lipids of cell-membranes are ordered in a bilayer structure. However, very little is known at present concerning the details of the interactions between different membrane components e.g. lipid-protein, lipid-lipid and protein-protein interactions. To investigate such interactions at the molecular level, spectroscopic methods have to be used. Magnetic resonance techniques (ESR and NMR) have been shown to be very potent tools for studies of both dynamic and structural properties of membranes [3,4]. Most of these studies have been performed on phospholipid model membranes [.5,6] . Furthermore, some criticism has been raised against the ESR spin label method used in many studies of natural membranes, since the perturbation of the system studied with this method cannot be neglected [5,7]. We have previously shown that deuteron NMR studies on model membrane systems can be used to investigate conformational changes of the choline group of synthetic lecithins [8] . In the present report this method has been adapted to the study of rat-liver cell-membranes where the lecithin and sphingomyelin is labeled in vivo with [Me-2 H] choline. This technique causes no distortion of the membrane and permits