Differential Scanning Calorimetric Study of Bilayer Membrane Phase Transitions. A Biophysical Chemistry Experiment

In a series of experiments designed for a biologically-oriented physical chemistry lab, the gel to liquid-crystalline phase transition of phospholipid bilayers is examined by differential scanning calorimetry. The four interrelated experiments examine the effect of altering lipid bilayer composition on the thermodynamic properties of the phase transition. Bilayer composition is modified by (i) varying the length of the phospholipid acyl chains, (ii) varying the identity of the phosphate headgroup, (iii) adding cholesterol, or (iv) mixing phospholipids of two different length acyl chains. Results relating bilayer structure to phase transitions for all experiments are presented, and the relationship of these experiments to the study of naturally occurring biomembranes is examined.