Isothermal Titration Calorimetry

Isothermal titration calorimetry (ITC) is a versatile and easy to use technique to study macromolecular interactions. Macromolecules interact with each other to perform biochemical functions. These interactions are commonly based on proteinligand binding interactions and may occur among peptide, DNA, RNA, lipid, carbohydrate, ion, antibody, and enzymes. ITC experiments are relatively easy to perform, and no labelling is required for the set up. Performing an ITC experiment not only gives binding parameter but also it provides thermodynamic data. Further, the thermodynamic data provides nature of the interaction at molecular level i.e. hydrogen bonding, hydrophobic interactions. Cooperativity of ligands and binding specificity of each site may be determined by this technique. Molecular weight range, number of interacting molecules, and optical clarity limit most of the instrumental techniques but ITC is not affected by these limitations. All these benefits make ITC a common method to determine binding constants. A combination of the technique with complementary methods augments its benefits in detecting molecular mechanism.

Keywords: Binding constant, Dissociation constant, Drug design, Entropy, Enthalpy, Food constituent analysis, Heat capacity, Protein-protein interaction, Protein-receptor interaction, Stoichiometry.