Deterministic error propagation in ITC: Revealing multi-fold errors in K_d values under standard conditions.

Area of Science:

• Biochemistry
• Biophysics
• Chemical Biology

Background:

• Accurate determination of equilibrium dissociation constant (K_d) is crucial for drug discovery and molecular diagnostics.
• Isothermal titration calorimetry (ITC) directly measures binding thermodynamics without labeling or immobilization.
• Systematic errors in experimental variables (analyte concentrations, measured heat) in ITC are often overlooked.

Purpose of the Study:

• To develop a deterministic framework for understanding error propagation in ITC-derived K_d.
• To quantify the impact of inaccuracies in analyte concentrations and measured heat on K_d determination.

Main Methods:

• Derivation of a closed-form mathematical model for error propagation in ITC.
• Quantification of the influence of systematic errors on K_d accuracy.

Main Results:

• Developed a mathematical model to assess error propagation in ITC K_d determination.
• Demonstrated that systematic errors in concentrations and heat can cause significant multi-fold deviations in K_d.
• These deviations occur even within the recommended c-value range (10-100) for ITC experiments.

Conclusions:

• Accurate K_d determination using ITC requires careful consideration of systematic errors.
• The derived framework highlights the need for quantitative accuracy assessments in ITC experiments.
• Practical tools are needed to support accurate ITC data evaluation and error assessment.