Molecular interaction. ITC can be used to provide information about interactions between different types of molecules, e.g., binding interactions or conformational changes. As an example, we will consider the use of ITS for quantifying the binding of a ligand molecule (L) to a protein molecule, (P): P + L … PL.A solution containing the ligand is placed into the injector, while a solution containing the protein is placed into the sample call. Small aliquots of the ligand solution are then injected into the sample solution at regular intervals (e.g., 10 mL every 300 seconds). The interval between each injection should be long enough to allow any reaction to go to completion. The instrument records the enthalpy change that occurs after each injection as a result of the interaction between the ligand and protein molecules. By measuring the change in the enthalpy with ligand sites on the protein, the strength of the binding interaction and the thermodynamics of the binding interaction.