title: High-precision isothermal titration calorimetry with automated peak-shape analysis.
abstract: Isothermal titration calorimetry (ITC) is a powerful classical method that enables researchers in many fields to study the thermodynamics of molecular interactions. Primary ITC data comprise the temporal evolution of differential power reporting the heat of reaction during a series of injections of aliquots of a reactant into a sample cell. By integration of each injection peak, an isotherm can be constructed of total changes in enthalpy as a function of changes in solution composition, which is rich in thermodynamic information on the reaction. However, the signals from the injection peaks are superimposed by the stochastically varying time-course of the instrumental baseline power, limiting the precision of ITC isotherms. Here, we describe a method for automated peak assignment based on peak-shape analysis via singular value decomposition in combination with detailed least-squares modeling of local pre- and postinjection baselines. This approach can effectively filter out contributions of short-term noise and adventitious events in the power trace. This method also provides, for the first time, statistical error estimates for the individual isotherm data points. In turn, this results in improved detection limits for high-affinity or low-enthalpy binding reactions and significantly higher precision of the derived thermodynamic parameters.
authors.affiliation: Molecular Biophysics, University of Kaiserslautern, 67663 Kaiserslautern, Germany.
authors.forename: Sandro
authors.initials: S
authors.lastname: Keller
authors.forename: Carolyn
authors.initials: C
authors.lastname: Vargas
authors.forename: Huaying
authors.initials: H
authors.lastname: Zhao
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Piszczek
authors.forename: Chad A
authors.initials: CA
authors.lastname: Brautigam
authors.forename: Peter
authors.initials: P
authors.lastname: Schuck
mesh_terms: D000818:Animals; D057205:Automation, Laboratory; D002151:Calorimetry / Q000379:methods*; D024402:Carbonic Anhydrase II / Q000032:analysis; D002417:Cattle; D017022:Flow Injection Analysis / Q000706:statistics & numerical data*; D006358:Hot Temperature; D016018:Least-Squares Analysis; D008698:Mesylates / Q000032:analysis; D013816:Thermodynamics
chemical_list: D008698:Mesylates; D024402:Carbonic Anhydrase II; C012077:trifluoromethanesulfonic acid