A unified framework based on the binding polynomial for characterizing biological systems by isothermal titration calorimetry

Methods. 2015 Apr;76:99-115. doi: 10.1016/j.ymeth.2014.09.010. Epub 2014 Oct 8.


Isothermal titration calorimetry (ITC) has become the gold-standard technique for studying binding processes due to its high precision and sensitivity, as well as its capability for the simultaneous determination of the association equilibrium constant, the binding enthalpy and the binding stoichiometry. The current widespread use of ITC for biological systems has been facilitated by technical advances and the availability of commercial calorimeters. However, the complexity of data analysis for non-standard models is one of the most significant drawbacks in ITC. Many models for studying macromolecular interactions can be found in the literature, but it looks like each biological system requires specific modeling and data analysis approaches. The aim of this article is to solve this lack of unity and provide a unified methodological framework for studying binding interactions by ITC that can be applied to any experimental system. The apparent complexity of this methodology, based on the binding polynomial, is overcome by its easy generalization to complex systems.

Keywords: Allosteric and polysteric linkage; Binding polynomial; Homotropic and heterotropic chemical linkage; Isothermal titration calorimetry; Ligand binding; Macromolecular interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Calcium / chemistry
  • Calorimetry / methods*
  • Carrier Proteins / chemistry
  • Edetic Acid / chemistry
  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • Thermodynamics
  • Viral Nonstructural Proteins / chemistry


  • Carrier Proteins
  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • NS3 protein, hepatitis C virus
  • NS4A cofactor peptide, Hepatitis C virus
  • Viral Nonstructural Proteins
  • Edetic Acid
  • Calcium