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Analysis Interactions of Metals Ions and biological molecules by Isothermal Titration Calorimetry (ITC) (CAT#: STEM-MB-2494-LGZ)

Introduction

The thermodynamics of metal ion binding to proteins and other biomolecules can be measured using isothermal titration calorimetry (ITC), which quantifies the binding enthalpy (ΔH°) and generates binding isotherms. Fitting of the isotherm provides the binding constant (K), allowing the free energy (ΔG°) and ultimately the binding entropy (ΔS°) to be determined. The temperature dependence of ΔH° can provide the change in heat capacity upon bonding (ΔC p°). However, measurements of metal binding by ITC can be affected by undesired reactions such as precipitation, hydrolysis, and redox, and often involve competing equilibria with buffers and protons, which contribute to experimental values (K ITC, ΔH ITC).




Principle

A reactant is placed in a temperature-controlled sample cell and coupled to the reference cell through a thermocouple loop. The sample cell and the reference cell are in the same external environment. A specific titration agent (selected as required by the test) is added to the sample cell quantitatively. The change in energy in response can be sensitively detected and triggered by a positive or negative feedback thermostat to keep the temperature constant.

Applications

For characterizing thermodynamic parameters of biomolecular interactions.

Procedure

1. Preparation before the experiment.
2. Add 40ul of ligand or small molecule protein solution to the titration syringe, 200ul of large molecule protein solution to the sample pool, and 200ul of distilled water to the reference pool.
3. Set Experimental Parameters in the interface.
4. In the set up interface, set the storage path of experimental data and experimental methods, as well as the current user.
5. Put the titration syringe into the sample pool and click Start to start the experiment. Display real-time images of the experiment on the Real Time Plot interface.

Materials

• Sample Type: protein 50 micrograms, small molecules 10mM/500ul, the higher the sample concentration is the better, protein peptides need to be sent at low temperature.
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