Isothermal Titration Calorimetry (ITC)

Isothermal titration calorimetry (ITC) is a method used to determine chemical and thermodynamic parameters of an interaction process between two components. Usually a measurement consists of an incremental titration, where a titrant is added stepwise to a sample of interest at certain time intervals. During this time the heat of the reaction being released or absorbed is being monitored via a power compensation measurement and then used to calculate binding affinities (K_a), reaction enthalpies (ΔH) and stoichiometries (N). This technique allows the examination of systems inside solution and therefore does not disturb any interactions through preparation methods.

Determination of:

• Association constant K_a
• Reaction enthalpy ΔH
• Reaction stoichiometry N

From those parameters the calculation of the Gibbs free energy ΔG and reaction entropy ΔS is possible. Thus, a complete thermodynamic characterization of a given binding process is possible. ITC is a nonstandard analysis technique, because each sample requires a method development.

Equipment / Sample requirements:

• Only liquids (aqueous solution and organic solvents possible)
• No aggregation during the reaction