Differential Scanning Calorimetry (DSC)
Differential Scanning Calorimetry is a powerful tool with which to perform a complete thermodynamic characterization of protein interactions and stability. The technique relies on the exposure of hydrophobic residues during the thermal denaturation of the protein. Exposure of hydrophobic groups to an aqueous solvent imposes an increased order on the surrounding hydration shell and ultimately results in the release of heat which the DSC instrument detects. Unlike circular dichroism, this technique does not rely on an optical measure of helicity, and as a result, provides a more sensitive measure of protein unfolding events that do not result in large changes in helicity.
DSC can be used to determine binding constants of protein-ligand interactions, and by extrapolation the enthalpy and heat capacity of binding. Since DSC allows one to determine ΔH and ΔCp of unfolding and binding, one can also calculate the free energies, ΔG, of unfolding and binding. ΔG measurements permit a direct comparison of the effects of point mutations on protein stability often critical in understanding disease states. Because DSC is sensitive to the formation of insoluble aggregates, and because, like AUC and SPR, it is a label-free technique, DSC is a standard tool in the characterization of biological molecules in both academic labs and within the biotech sector.