Calorimetric investigations of lipid phase transitions. I. The width of transition

Abstract

Calorimetric calibration measurements with electrical heat pulses and with the crystallization process of hexadecane have been performed. It is shown that only under favorable conditions and for the lowest scanning rates is it possible to determine the true width of the main phase transition of aqueous dispersions of multilamellar dimyristoyllecithin-liposomes. Hence a cooperative unit involving more than 1700 molecules is deduced which is indicative of a first-order phase transition with only very little impurity broadening.