Titration Calorimetry and Differential Scanning Calorimetry of Lipid–Protein Interactions
A living cell is surrounded by a thin membrane of (5–15) nm thickness which separates it from the environment. The basic building stone of this membrane is a hydrophobic lipid bilayer in which transport proteins are embedded. The lipid fraction varies between (20–80)%. The interaction of proteins with the lipid membrane is conveniently studied with calorimetric methods. High sensitivity titration calorimetry (ITC) is the method of choice to quantitate the thermodynamic binding parameters of lipid–protein interaction. In contrast, differential scanning calorimetry (DSC) is the reference method for the thermal stability of proteins. The principles of ITC and DSC are explained and illustrated with a small peptide and a cholesterol-transporting protein.