On the Nature of Interactions between Ionic Liquids and Small Amino‐Acid‐Based Biomolecules

Abstract

During the last decade, ionic liquids (ILs) have revealed promising properties and applications in many research fields, including biotechnology and biological sciences. The focus of this contribution is to give a critical review of the phenomena observed and current knowledge of the interactions occurring on a molecular basis. As opposed to the huge advances made in understanding the properties of proteins in ILs, complementary investigations dealing with interactions between ILs and peptides or oligopeptides are underrepresented and are mostly only of phenomenological nature. However, the field has received more attention in the last few years. This Review features a meta-analysis of the available data and findings and should, therefore, provide a basis for a scientifically profound understanding of the nature and mechanisms of interactions between ILs and structured or nonstructured peptides. Fundamental aspects of the interactions between different peptides/oligopeptides and ILs are complemented by sections on the experimental (spectroscopy, structural biology) and theoretical (computational chemistry) possibilities to explain the phenomena reported so far in the literature. In effect, this should lead to the development of novel applications and support the understanding of IL-solute interactions in general.

Suppression Effect on the Formation of Insulin Amyloid by the Use of Ionic Liquids

“…[9][10][11][12][13] ILs can be designed by varying cations and anions to obtain different solvent properties such as the chaotropes and kosmotropes for protein stability along the Hofmeister series. 14 In particular, the condensed IL solutions act as an inhibitor for heat aggregation of proteins 15,16 and are directly able to control the electrostatic interactions in proteins through the IL-protein interaction. 17 Thus, addition of condensed ILs solutions to the protein is expected to suppress amyloid formation.…”

“…14 and their concentrated solutions caused α-helix formation without protein aggregation for proteins such as β-lactoglobuin and cytochrome c. 31,32 In this study, we have investigated the effect of addition of these three ILs on the suppression of bovine insulin amyloids formation in the wide range of IL concentrations (X (mol%IL) = 0-30) using congo red (CR) assay and Fourier transform infrared (FTIR) spectroscopy. Moreover, we have discussed its mechanism from the viewpoint of IL-insulin interaction using five model proteins: β-lactoglobulin, myoglobin, lysozyme, ribonuclease A, and cytochrome c. These five proteins were used to evaluate the generality of the IL-protein interaction site because they have different secondary structure contents and protein sizes, and 4 their structural transitions and amyloid formation are well known.…”

Modification of Rapana thomasiana hemocyanin with choline amino acid salts significantly enhances its antiproliferative activity against MCF-7 human breast cancer cells

“…For example, Byrne and Angell have found that ethyl ammonium nitrate is able to recover egg while lysozyme conformation and activity aer severe denaturation leading to bril formation. 19,20 All this implies that ILs, especially those consisting of non-toxic and biocompatible cations and anions, may have potential to stabilize therapeutic proteins. enhancing kinetic stability of the lysozyme.…”

Ionic Liquids Beyond Simple Solvents: Glimpses at the State of the Art in Organic Chemistry

“…Interestingly, for cations, everything seems to be “upside down”: kosmotropic cations that stabilize the native structure of water destabilize proteins, while chaotropic cations stabilize the proteins. An overview on the nature of interactions between ILs and small peptides has been assembled by Tietze and co‐workers …”