Differential Thermal Analysis of Phospholipids

Abstract

FOR many years the melting points of both synthetic and natural phospholipids have been measured and recorded^1–3. An examination of a given class of phospholipids reveals that these melting points are, to a large extent, independent of the fatty acid residues present. Thus, 2-oleoyl-3-stearoyl-L-1-phosphatidylcholine and 2,3-distearoyl-L-1-phosphatidylcholine both have recorded melting points³ of 230°–231° C. The thermal transitions of phospholipids are difficult to observe with normal melting equipment, even when using a microscope. Occasionally some workers have observed ‘sintering points’, corresponding to thermal transitions, which occur below the normal melting point. However, the relevance of these points has never been demonstrated.