2022/11/04 by Shilpa Mohanakumar, Mohanakumar, Shilpa, Namkyu Lee +3
Agricultural and Biological Sciences · Chemistry · Engineering · #Bee Products Chemical Analysis #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Field-Flow Fractionation Techniques #Soft Condensed Matter (cond-mat.soft) #Statistical Mechanics (cond-mat.stat-mech) #thermodynamics and calorimetric analyses
paper · doi:10.48550/arxiv.2211.02343
openalex publication_date 2022/11/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In recent years, thermophoresis has emerged as a promising tool for quantifying biomolecular interactions. The underlying physical effect is still not understood. To gain deeper insight, we investigate whether non-equilibrium coefficients can be related to equilibrium properties. Therefore, we compare thermophoretic data measured by thermal diffusion forced Rayleigh scattering (TDFRS) (which is a non-equilibrium process) with thermodynamic data obtained by isothermal titration calorimetry (ITC) (which is an equilibrium process). As a reference system, we studied chelation reaction between ethylenediaminetetraacetic acid (EDTA) and calcium chloride (CaCl2) to relate the thermophoretic behavior quantified by the Soret coefficient S\mathrm T to the Gibb's free energy ΔG determined in the ITC experiment using an expression proposed by Eastman [J. Am. Chem. Soc. 50, 283 (1928)]. Finally, we have studied the binding of the protein Bovine Carbonic Anhydrase I (BCA I) to two different benzenesulfonamide derivatives: 4-fluorobenzenesulfonamide (4FBS) and pentafluorobenzenesulfonamide (PFBS). For all three systems, we find that the Gibb' free energies calculated from S\mathrm T agree with ΔG from the ITC experiment. In addition, we also investigate the influence of fluorescent labeling, which allows measurements in a thermophoretic microfluidic cell. Re-examination of the fluorescently labeled system using ITC showed a strong influence of the dye on the binding behavior.