Lipid organization and dynamics of the monostearoylglycerol-water system. A 2H NMR study.

Deuterium labeled monostearoylglycerols with fully ([2H(35)]-MSG) and selectively ([11-(2)H(2)]-MSG) deuterated chains have been synthesized and used as a probe for 2H NMR. At low temperature monoglyceride-water systems form the coagel or crystalline phase, which transforms with increasing temperature subsequently into the gel, liquid crystalline and cubic phase. The 2H NMR spectra exhibit characteristic features representative of these phases. The gel phase is metastable and gradually transforms into the coagel at temperatures below 40 degrees C. The undercooled cubic phase transforms into the liquid crystalline phase during days. In the liquid crystalline phase, the chain order profile indicates an increase of the chain flexibility towards the methyl group. In the liquid crystalline phase, bilayers spontaneously align in a magnetic field with their normal perpendicular to the field. The results demonstrate that 2H NMR can serve as a convenient tool to study both structure and dynamics of different monoglyceride-water phases.