Affinity and thermodynamic parameters of interaction between DH domain of VAV2 protein and CDC42 protein

Abstract:

Objective: To study the interaction between the DH domain of VAV2 protein (VAV2-DH) and CDC42 by isothermal titration calorimetry. Methods: The coding sequences of VAV2-DH and CDC42 were cloned into pGEX-6p-1 or pET28a vectors to construct recombinant prokaryotic expression plasmids. Purified proteins were obtained by prokaryotic expression, affinity chromatography and gel filtration chromatography. Then GEF assay and isothermal titration calorimetry were employed to detect the affinity and thermodynamic parameters of the interaction between VAV2-DH and CDC42. Results: Moderate binding affinity was recorded between VAV2-DH and CDC42 with a K_Dvalue of (11.44±2.12) μmol/L, in which the molar binding enthalpy DH= (-224.33±95.48) kJ/mol, -TDS= (195.97±95.95) kJ/mol, and Gibbs free energy DG= (-28.30±0.49) kJ/mol. Conclusion: VAV2-DH and CDC42 protein interact with each other with moderate intensity, which is an enthalpy-driven binding process.