THERMODIFFUSION AS A PROBE FOR PROTEIN HYDRATION

Niether, Doreen; Stadler, Andreas; Wiegand, Simone; Sarter, Mona

Conference Presentation (After Call)

FZJ-2018-05999

THERMODIFFUSION AS A PROBE FOR PROTEIN HYDRATION

Niether, D. (Corresponding author)FZJ* ; Sarter, M.FZJ* ; Stadler, A.FZJ* ; Wiegand, S.FZJ*

2018

13th International Meeting on Thermodiffusion, IMT13, London, UK, 11 Sep 2018 - 14 Sep 2018

Please use a persistent id in citations: http://hdl.handle.net/2128/20987

Abstract: Protein-ligand interactions are of fundamental importance to numerous processes in living organisms. A very sensitive method to observe the reaction kinetics is Microscale thermophoresis (MST), which uses the changed thermophoretic behaviour as an indicator for complex formation [1]. This sensitivity of thermodiffusion is attributed to modifications in the hydration shell of the protein upon complex formation, which can be strong due to conformational changes of the protein. There is, however, no detailed understanding how protein conformation, hydration and thermophoretic behaviour are connected. Our aim is to elucidate that point and find out if MST could be used to obtain information about protein hydration in addition to the reaction kinetics. Several cyclodextrins and their complexes with acetylsalicylic acid were investigated as a simple model system [2]. We found that the temperature dependence of a solute’s thermodiffusion is correlated to its hydrophilicity, but the observed change upon complex formation is relatively small due to the rigidity of cyclodextrin. The second model system is the protein streptavidin and its complex with biotin [3]. Data from quasi-elastic neutron scattering (QENS) and isothermal titration calorimetry (ITC) show a reduced entropy of the complex in comparison to the free protein, which is partly compensated by an increased entropy of the hydration shell. This is in agreement with a breaking of hydrogen bonds between protein and surrounding water due to the reduced flexibility of the protein [4] and fits with the reduced hydrophilicity of the complex indicated by thermodiffusion.REFERENCES[1] M. Jerabek-Willemsen et al., J. Mol. Struct. 1077, 101-113 (2014)[2] D. Niether et al., Langmuir, 33, 8483 (2017).[3] D. Niether et al., AIP Conference Proceedings 1929, 020001 (2018).[4] S. Liese et al., ACS Nano, 11 702 (2017).

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