Calorimetric and freeze-etch study of the influence of Mg2+ on the thermotropic behaviour of phosphatidylglycerol

In the presence of Mg2+ ions phosphatidylglycerol shows supercooling which leads to the formation of a metastable gel phase. This contrasts with the behaviour of this negatively charged phospholipid in the presence of Ca2+ ions (Biochim. Biophys. Acta 339 (1974) 432). It is demonstrated that the heat content of this phospholipid is dependent on the ionic environment