Studies of the lipid phase transitions of Escherichia coli by high sensitivity differential scanning calorimetry.

High sensitivity adiabatic differential scanning calorimetry was performed on lipids, membrane vesicles, and whole cells of Escherichia coli enriched in particular unsaturated fatty acids by genetic means. Information concerning the shape of the transition is discussed. Transitions with an asymmetric shape reminiscient of a second order transition were observed. Comparison between the lipid transition observed in whole cells, membrane vesicles, and extracted lipids enriched in elaidate reveal some basic similarities. Studies of synthetic lipids were undertaken in an attempt to interpret the shapes of these transitions as a function of the lipid components of the membrane.