The determination of the phase diagram for a DMPC/DSPC lipid mixture using 2H NMR difference spectroscopy

Abstract

A technique called deuterium NMR difference spectroscopy was used to determine the phase diagram for a mixture of two different lipids. The two lipids studied were dimyristoylphosphatidylcholine (DMPC) and distearoylphosphatidylcholine (DSPC). Since deuterium NMR was used to acquire the data, the DMPC lipid's hydrocarbon chains were deuterated to yield DMPCd54. The lipid, at low temperatures, is in the gel phase and passes into the liquid crystalline phase as the temperature is raised. Experiments were conducted on mixtures with a variety of lipid concentrations at temperatures ranging from 4°c-so0 c. The corresponding spectra obtained using 2H NMR were used to calculate the endpoints of the phase boundaries at each temperature. These endpoints determined the phase diagram for the DMPC/DSPC mixture.