In Isothermal Titration Calorimetry (ITC) heat changes associated with chemical reactions are monitored. It is a powerful, label-free, direct method to observe the thermodynamics of binding reactions and to directly characterize enzyme kinetics.
The binding constant (Ka), the stoichiometry (n), ΔH, ΔG, and ΔS can be determined from a single binding experiment. Δcp can be determined from the temperature dependency of ΔH observed in multiple experiments at different temperatures. ITC of enzyme-substrate reactions can be used to determine KM and kcat.
Exciting Possibilities in Biology, Biochemistry and Biophysics
Ka, ΔH, ΔG, ΔS,Δcp (protein-protein, protein-ligand, DNA/RNA-ligand, DNA/RNA-protein, protein-lipids, peptide-lipids...)
Measure heat directly
Avoid coupled enzyme assay or standard curves
Avoid labeling or immobilization
Use turbid or colored solutions
Determine multiple binding affinities and stoichiometries in one system