Analyze binding heats with practical thermodynamic fitting guidance. Estimate affinity, entropy, and signal quality clearly. Plan stronger titration studies with clearer thermodynamic confidence today.
| Parameter | Example Value | Unit | Purpose |
|---|---|---|---|
| Cell Volume | 1.40 | mL | Reaction cell working volume |
| Macromolecule Concentration | 50 | µM | Binding partner inside the cell |
| Ligand Concentration | 1.00 | mM | Syringe analyte concentration |
| Injections | 20 | count | Total titration steps |
| Injection Volume | 2.0 | µL | Volume per step |
| Kd | 5.0 | µM | Apparent dissociation constant |
| ΔH | -8.5 | kcal/mol | Binding enthalpy |
| Baseline Noise | 0.30 | µJ | Approximate instrumental noise |
1. Wiseman c-value: c = (n × Mcell) / Kd. This gauges whether the experiment sits in a useful binding window.
2. Fraction bound estimate: f = r / ((Kd / M) + r), where r is the chosen ligand-to-macromolecule ratio.
3. Maximum heat: Qmax = |ΔH| × moles of macromolecule × min(r, n). The result is converted from calories into microjoules.
4. Free energy: ΔG = R × T × ln(Kd), using Kd in molar units and T in kelvin.
5. Entropy: ΔS = (ΔH - ΔG) / T. This separates the energetic balance into enthalpic and entropic contributions.
6. Final molar ratio: ratio = total ligand added / (initial macromolecule moles × n).
7. Confidence ranges: practical uncertainty is approximated from c-value strength, signal-to-noise, and the chosen confidence percentage.
The c-value compares effective binding strength against concentration in the cell. Very low values often weaken curve shape, while extremely high values can compress transition regions and complicate parameter estimation.
No. This calculator is a planning and interpretation aid. It estimates expected behavior from supplied parameters, but dedicated ITC analysis software remains better for fitting raw injection heats directly.
Micromolar input is convenient for many biochemical datasets. The calculator converts it to molar units internally before applying thermodynamic equations involving logarithms and temperature-dependent free energy.
Heat peaks near the instrument baseline are harder to distinguish from drift and noise. Better signal-to-noise usually improves confidence in ΔH, Kd, stoichiometry, and the overall fitted transition.
That often suggests weak concentration leverage. You may need higher macromolecule concentration, lower Kd systems, different cell loading, or revised titrant concentration to obtain a sharper binding curve.
Yes. Positive or negative ΔH values are allowed. The sign changes the heat direction, while absolute magnitude affects predicted signal size and practical detectability against the chosen baseline noise.
The recommendation estimates a syringe concentration that better reaches your chosen final molar ratio using the specified number of injections and injection volume. It helps with experiment design.
No. They are practical approximations based on experiment strength indicators. Use them as guidance for planning and screening, then confirm uncertainty from raw-data fitting and replicate experiments.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.