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, ΔHΔGΔS, 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
  • Enzyme kinetics, KM, kcat (in some cases)
  • Inhibitor studies, KI
  • Folding reactions (proteins, RNA, DNA)
  • And a lot more...