Lipid-phase transition of phosphatidylglycerol in Acholeplasma laidlawii membranes studied with phospholipase A2.

Phospholipase A2 was applied to follow the lipid phase transition of phosphatidylglycerol in the membrane of Acholeplasma laidlawii. The conclusions were identical with those obtained with physicochemical techniques. In addition, it was shown that phosphatidylglycerol undergoes the lipid phase transition in the same temperature range as the bulk of the membrane lipid; phase segregation between various molecular species of phosphatidylglycerol occurs; exchange of this phospholipid between rigid and fluid domains is a slow, temperature-dependent process; and phosphatidylglycerol-protein interactions do occur at temperatures above that of the lipid phase transition.