Synthesis of Perdeuterated 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine ([D82]POPC) and Characterisation of Its Lipid Bilayer Membrane Structure by Neutron Reflectometry

1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), an unsaturated acyl chain containing lipid, is often the predominant lipid in eukaryotic cell membranes in which it is crucial for the fluidity of membranes under physiological conditions. Commercially available, partially deuterated [D-31]1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine ([D-31]POPC) does not provide sufficient isotopic contrast for detailed structural studies of multicomponent membranes through neutron techniques. Herein, a relatively straightforward and generic chemical deuteration method is discussed for the asymmetric synthesis of perdeuterated [D-31]1-palmitoyl-[D-33]2-oleoyl-sn-[D-5]glycero-[D-13]3-phosphocholine ([D-82]POPC) that also allows selective deuteration of any of its constituent groups. Neutron reflectivity of a [D-82]POPC-supported bilayer was used to experimentally determine the neutron scattering length density profile of the lipid. The acyl chains of [D-82]POPC are closely contrast-matched to heavy water, whereas the very high scattering length density of the deuterated glycerophosphocholine head groups provides good contrast to membrane-binding agents in both deuterated and non-deuterated solvent environments.