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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 42: Charged Soft Matter, Ionic Liquids and Polyions I

CPP 42.5: Hauptvortrag

Mittwoch, 22. März 2017, 16:00–16:30, ZEU 114

Aqueous Ionic Liquids and Their Influence on Peptide Conformations: Denaturation and Dehydration Mechanisms — •Jens Smiatek — Institut für Coputerphysik, Universität Stuttgart, D-70569 Stuttgart, Germany

The influence of low concentrated aqueous ionic liquid (ILs) solutions on protein structures has attracted a lot of interest in the last years. This can be mostly attributed to the distinct roles of the aqueous ILs as protein protectants or protein denaturants. I will review the results of atomistic molecular dynamics (MD) simulations to study the influence of different ILs on the conformational properties of a short hairpin peptide. The results reveal distinct binding and denaturation effects for 1-ethyl-3-methylimidazolium (EMIM) in combination with the different anions chloride (CL), tetrafluoroborate (BF4) and acetate (ACE). The simulation outcomes indicate that ILs with larger anions induce a stronger dehydration effect which is accomplished by a more pronounced accumulation behavior of the individual ion species around the peptide. All findings can be related 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 outcomes of this analysis are in good agreement with the results of metadynamics simulations to determine the energetically most favorable conformations of the peptide in presence of the individual aqueous ILs. All findings indicate that the denaturation strength decreases in the order EMIM/ACE, EMIM/BF4 and EMIM/CL, which coincides with the size of the anion species.