Isothermal titration calorimetry for drug design: Precision of the enthalpy and binding constant measurements and comparison of theinstruments. Anal Biochem. 2016; 515:61-64.
Vaida Linkuvien, Georg Krainer, Wen-Yih Chen, Daumantas Matulis
ABSTRACT: Isothermal titration calorimetry (ITC) is one of the most robust label- and immobilization-free techniques used to measure protein e small molecule interactions in drug design for the simultaneous determination of the binding affinity (∆G) and the enthalpy (∆H), both of which are important parameters for structure-thermodynamics correlations. It is important to evaluate the precision of the method and of various ITC instrument models by performing a single well-characterized reaction. The binding between carbonic anhydrase II and acetazolamide was measured by four ITC instruments e PEAQ-ITC, iTC200, VPITC, and MCS-ITC and the standard deviation of ∆G and ∆H was determined. Furthermore, the limit of an approach to reduce the protein concentration was studied for a high-affinity reaction (Kd = 0.3 nM), too tight to be measured by direct (non-displacement) ITC. Chemical validation of the enthalpy measurements is discussed.