Aqueous ionic liquids and their influence on peptide conformations: denaturation and dehydration mechanisms

Diddens, Diddo; Smiatek, Jens; Lesch, Volker; Heuer, Andreas

doi:10.1039/C7CP02897K

Journal Article

FZJ-2018-02866

Aqueous ionic liquids and their influence on peptide conformations: denaturation and dehydration mechanisms

Diddens, D.FZJ* ; Lesch, V. ; Heuer, A.FZJ* ; Smiatek, J. (Corresponding author)FZJ*

2017
RSC Publ. Cambridge

Physical chemistry, chemical physics 19(31), 20430 - 20440 (2017) [10.1039/C7CP02897K]

This record in other databases:

Please use a persistent id in citations: doi:10.1039/C7CP02897K

Abstract: Low concentrated aqueous ionic liquids (ILs) and their influence on protein structures have attracted a lot of interest over the last few years. This can be mostly attributed to the fact that aqueous ILs, depending on the ion species involved, can be used as protein protectants or protein denaturants. Atomistic molecular dynamics (MD) simulations are performed in order to study the influence of different aprotic ILs on the properties of a short hairpin peptide. Our results reveal distinct binding and denaturation effects for 1-ethyl-3-methylimidazolium (EMIM) in combination with different anions, namely, chloride (CL), tetrafluoroborate (BF4) and acetate (ACE). The simulation outcomes demonstrate that the studied ILs with larger anions reveal a more pronounced accumulation behavior of the individual ion species around the peptide, which is accomplished by a stronger dehydration effect. We can relate these findings to the implications of the Kirkwood–Buff theory, which provides a thermodynamic explanation for the denaturation strength in terms of the IL accumulation behavior. The results for the spatial distribution functions, the binding energies and the local/bulk partition coefficients are in good agreement with metadynamics simulations in order to determine the energetically most stable peptide conformations. The free energy landscapes indicate a decrease of the denaturation strength in the order EMIM/ACE, EMIM/BF4 and EMIM/CL, which coincides with a decreasing size of the anion species. An analysis of the potential binding energies reveals that this effect is mainly of enthalpic nature.

Classification: