Isothermal Titration Calorimetry

Isothermal titration calorimetry (ITC) is a gold standard physical technique used to determine the thermodynamic parameters of interactions in solution. This label free technique is based on the precise measurement of heat absorbed or generated during binding events in a sequential (titrating) manner.

Comparing with other techniques of studying biomolecular interactions, ITC is distinguished by several advantages: 1) It does not need any chemical modification or immobilization of either binding partner, 2) Molecular weight of reactants is not limited, and 3) It is unaffected by the spectroscopic properties of reactants.

Figure 1. Configuration of an ITC reaction cell and a typical ITC experiment
(Physical Chemistry Research, 2015)

During a single experiment, ITC allows simultaneous determination of binding constants (Ka), reaction stoichiometry (n), and enthalpy (∆H) and entropy (∆S) change of the investigated interaction. The principle is the measurement of the amount of power that is used to maintain the same temperature between the sample cell and reference cell per unit of time. Due to the ease of use and comprehensive quantification capability, ITC has been widely used in many research fields: i) Protein-ligand interactions. e.g., interaction of proteins with various ligands including small molecules, metal ions, drugs, enzyme inhibitors etc. ii) Protein-protein interactions. e.g., domain-domain interaction, protein recognition, hormone-receptor, antibody-antigen, antibody-receptor binding and membrane fusion. iii) Self association. e.g., micellization parameters of surfactants in aqueous solutions. iv) Other chemical and physical processes involved in biomedical and drug development.

Profacgen’s service is powered by our best knowledge of physical chemistry and structural biology, as well as advanced analysis instruments, including MicroCal iTC200.

Profacgen offers professional one-stop services for isothermal titration calorimetry measurement:

• High sensitivity for binding constant as low as nM;
• Small sample quantities as low as 20 µM;
• Full service packing from sample preparation to data analysis;
• Regular ITC assays;
• Data fitting and interpretation;
• Quantification and characterization based on molecular mechanisms.

References:

1. Atri, M.S., Saboury, A.A., Ahmad, F. (2015) Biological applications of isothermal titration calorimetry. Physical Chemistry Research. 3: 319-330.

2. Liang, Y. (2008) Applications of isothermal titration calorimetry in protein science. Acta Biochimica et Biophysica Sinica. 40: 565-576.