TY - JOUR
T1 - Modeling complex equilibria in isothermal titration calorimetry experiments
T2 - Thermodynamic parameters estimation for a three-binding-site model
AU - Le, Vu H.
AU - Buscaglia, Robert
AU - Chaires, Jonathan B.
AU - Lewis, Edwin A.
N1 - Funding Information:
The work was supported in part by Grant CA35635 from the National Cancer Institute (to J.B.C.) and by the James Graham Brown Foundation.
PY - 2013/3/15
Y1 - 2013/3/15
N2 - Isothermal titration calorimetry (ITC) is a powerful technique that can be used to estimate a complete set of thermodynamic parameters (e.g., K eq (or ΔG), ΔH, ΔS, and n) for a ligand-binding interaction described by a thermodynamic model. Thermodynamic models are constructed by combining equilibrium constant, mass balance, and charge balance equations for the system under study. Commercial ITC instruments are supplied with software that includes a number of simple interaction models, for example, one binding site, two binding sites, sequential sites, and n-independent binding sites. More complex models, for example, three or more binding sites, one site with multiple binding mechanisms, linked equilibria, or equilibria involving macromolecular conformational selection through ligand binding, need to be developed on a case-by-case basis by the ITC user. In this paper we provide an algorithm (and a link to our MATLAB program) for the nonlinear regression analysis of a multiple-binding-site model with up to four overlapping binding equilibria. Error analysis demonstrates that fitting ITC data for multiple parameters (e.g., up to nine parameters in the three-binding-site model) yields thermodynamic parameters with acceptable accuracy.
AB - Isothermal titration calorimetry (ITC) is a powerful technique that can be used to estimate a complete set of thermodynamic parameters (e.g., K eq (or ΔG), ΔH, ΔS, and n) for a ligand-binding interaction described by a thermodynamic model. Thermodynamic models are constructed by combining equilibrium constant, mass balance, and charge balance equations for the system under study. Commercial ITC instruments are supplied with software that includes a number of simple interaction models, for example, one binding site, two binding sites, sequential sites, and n-independent binding sites. More complex models, for example, three or more binding sites, one site with multiple binding mechanisms, linked equilibria, or equilibria involving macromolecular conformational selection through ligand binding, need to be developed on a case-by-case basis by the ITC user. In this paper we provide an algorithm (and a link to our MATLAB program) for the nonlinear regression analysis of a multiple-binding-site model with up to four overlapping binding equilibria. Error analysis demonstrates that fitting ITC data for multiple parameters (e.g., up to nine parameters in the three-binding-site model) yields thermodynamic parameters with acceptable accuracy.
KW - Analysis
KW - Calorimetry
KW - Fitting
KW - ITC
KW - Multiple binding sites
KW - Nonlinear regression
KW - Three-binding-site model
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U2 - 10.1016/j.ab.2012.11.030
DO - 10.1016/j.ab.2012.11.030
M3 - Article
C2 - 23262283
AN - SCOPUS:84873348065
SN - 0003-2697
VL - 434
SP - 233
EP - 241
JO - Analytical Biochemistry
JF - Analytical Biochemistry
IS - 2
ER -