Thermophoresis of biological compounds in aqueous media
Thermophoresis, or thermodiffusion, is mass transport driven by a temperature gradient. Our work focuses on thermodiffusion in a biological context, where there are two major applications for the effect: accumulation of a component in microfluidic devices through a combination of thermodiffusion and convection, and monitoring of protein binding reactions through the sensitivity of thermodiffusion to complex formation. Both applications are investigated, the first as an accumulation process in the context of origin-of-life theories and the second in light of the question what we can learn from the observed changes in thermodiffusion about modifications of the hydration shell upon complex formation such as during a protein-ligand binding process. For non-ionic compounds we find a clear correlation between hydrophilicity and temperature sensitivity of the thermophoretic behaviour, which can be used to determine partition coefficients for complex biomolecules, where the incremental method fails, because a part of the folded biomolecules is not accessible by the solvent. The thermophoretic study of ions reveal ion specific hydration, which are crucial in biological information processes. Performing systematic thermophoretic measurements in combination with neutron scattering experiments and isothermal titration experiments we gain a deeper insight into entropic and enthalpic changes of the protein, protein-ligand complex and accompanied hydration layer upon binding. In quantifying biomolecular bonding, we have established a relationship between the energy released in a reaction and the concentration difference formed in a temperature gradient. This is an important step towards understanding non-equilibrium processes, as they also occur in the human body.
thermodiffusion, thermophoresis, hydration, hydrophilicity, ion specific effects, origin of life, separation techniques, Scattering techniques
Prof. Dr. Simone Wiegand
Building 04.6 / Room 76
Complementary Experimental Methods to Obtain Thermodynamic Parameters of Protein Ligand Systems. S. Mohanakumar and S. Wiegand, Int. J. Mol. Sci. 23, 14198 (2022). DOI: 10.3390/ijms232214198
Overlapping hydration shells in salt solutions causing non-monotonic Soret coefficients with varying concentration. S. Mohanakumar, H. Kriegs, W.J. Briels and S. Wiegand, Phys. Chem. Chem. Phys. 24, 27380 (2022). DOI: 10.1039/D2CP04089A
Thermophoretic Micron-Scale Devices: Practical Approach and Review. N. Lee and S. Wiegand, Entropy 22, 950 (2020). DOI: 10.3390/e22090950
Thermophoresis of biological and biocompatible compounds in aqueous solution.
Niether, D. and Wiegand, S., J. Phys. Condens. Matter 31, 503003 (2019). DOI: 10.1088/1361-648X/ab421c
Accumulation of formamide in hydrothermal pores to form prebiotic nucleobases.
D. Niether, D et al., Proc Natl Acad Sci USA 113, 4272 (2016). DOI: 10.1073/pnas.1600275113