Impact of the Alkyl Side Chains of Cations and Anions on the Activity and Renaturation of Lysozyme: A Systematic Study Performed Using Six Amino‐Acid‐Based Ionic Liquids

Abstract The impact of the structure of ionic liquid on the activity and renaturation of lysozyme from the hen egg white (HEWL) was investigated. A set of six ionic liquids based on morpholinium cation and N ‐acylated amino acids as anions were exploited. The matrix used was based on two homologous series: one with N ‐acetyl‐ L ‐valinate [Val] as a common anion and morpholinium cation with a different number of carbon atoms in the n‐alkyl chain (n=2, 4, 6, 8); and second, a common N‐ butyl‐ N ‐methylmorpholinium cation and different N ‐acylated amino acids. Interactions of ionic liquids with HEWL were explored by analyzing the changes in the activity of the enzyme based on the rate of hydrolysis of a β‐1,4 ‐glycosidic bond between components of peptidoglycan in the cell wall of Micrococcus luteus bacteria. The results demonstrated various mechanisms of interaction of cations and anions with HEWL, and hence, different trends in the association between the number of carbon atoms and the given property.