Isothermal Titration Calorimetry (ITC)
Isothermal Titration Calorimetry provides the researcher with a simple, robust and accurate technique to completely determine the thermodynamics of protein-protein or protein-ligand interactions. ITC involves the titration of small-molecule or protein analytes, into a solution containing the appropriate ligand or binding partner. Protein-analyte or protein-ligand binding interactions result in either exposure, or protection of hydrophobic regions on the protein surface, which in turn, results in a re-organization of the hydration shell around the protein. The micro-calorimeter, (Microcal ITC-200), measures the resulting heat exchange as a function of analyte concentration.
This technique provides a direct label-free method to measure dissociation constants, and to determine the stoichiometry of protein interactions. Like DSC, ITC is capable of measuring thermodynamic parameters associated with binding such as the enthalpy and entropy of binding.