Ionic liquids as novel reaction media for the chemical synthesis of peptides

Abstract

To seek the best solvent in which the peptide can dissolve is usually a serious challenge in peptide chemical synthesis. Ionic liquids, which are liquid below 100 °C, or even at room temperature, showed an outstanding solubility for polar compounds, unpolar compounds and even biological macromolecules. Furthermore, ionic liquids are also recognized as a green solvent because of their special properties, such as non-flammability, thermal/chemical stability, no measurable vapor pressure and recyclability. Thus, ionic liquids have attracted increasing interest in the field of peptide synthesis. In this thesis, the compatibility of ionic liquids for the Native Chemical Ligation strategy at a X–Cys ligation site (X = any amino acid) was analyzed and compared to the conventional ligation strategy. Besides that, the initial attempts of lactam bridge formation of cyclic peptides in ionic liquid have been made with the aim to complete the insufficient knowledge regarding peptide cyclization in ionic liquids. In conclusion, this thesis obtains an impression on how the application of ionic liquids for both reaction types provides essential contributions to the field of peptide chemistry employing alternative reaction media.