Isothermal Titration Calorimetry

The High Throughput Screening Resource Center has a GE Microcal auto-ITC200 for performing automated isothermal titration calorimetry. The technique measures small changes in heat capacity in a fixed volume of solution under constant temperature and pressure. Such changes occur when chemical bonds are formed or broken, such as those which occur during small molecule binding to a receptor. By performing a titration experiment one can measure the affinity and change in heat capacity and thus can determine all binding parameters (stoichiometry, dissociation constants, enthalpy change and entropy change) in a single experiment. The system requires purified biomolecules or compounds of defined concentration in the micromolar range in order to work optimally.

The auto-ITC200 is designed for ease-of-use,all functions being operated through software to facilitate fast and accurate analyses. Applications include: characterization of molecular interactions of small molecules, proteins, antibodies, nucleic acids, lipids and other biomolecules, enzyme kinetics and the assessment of the effect of molecular structure changes on binding mechanisms. Experiments require only 200-400 μl of sample. Samples generally should be in the 1-50 μM range for detection of significant changes in molar heat capacity. No immobilization or labeling is required. The iTC200can provide sample throughput of up to 50 samples per day with a capacity to process as many as 384 samples unattended.