The accumulation of amyloids is associated with various diseases such as Alzheimer’s disease, type II diabetes or hereditary systemic amyloidosis [1]. Finding that the ability to form amyloid aggregates is generic property of polypeptide chain [2] has extended the focus also on other proteins not related to any diseases. As an example, amyloid fibrils have been tested as novel biomaterials due to their properties such as elasticity and stability [3]. The solvent properties play an important role in controlling self-assembly process in vitro. Novel class of solvents – ionic liquids (ILs) have been found to alter the self-assembly of proteins. We have studied the effect of ionic liquids with 1-ethyl-3-methylimidazolium as cation combined with two different anions – tetrafluoroborate and acetate - on kinetics of lysozyme amyloid fibrillization (thioflavin fluorescence assay, CD spectroscopy) and morphology of formed fibrils (AFM, image analysis [4]). We have found that both used ILs at concentrations from 0.5-5% in water pH 2.5 are able to trigger lysozyme fibrillization at low protein concentration. The different nature of used anions has only slight effect manifested by broader kinetics pattern with lesser steepness, larger lag phase, longer time needed for achievement of steady-state intensity and lower abundance of β-sheet structures at presence of kosmotropic acetate anion. The height distribution of fibril ridges is from shorter range 3-10 nm for acetate than for tetrafluoroborate with larger filament ridge heights about 15 nm. We have found that lysozyme amyloid fibrillization kinetics and morphology can be modulated by ILs.
The work was supported by Slovak grant agency VEGA n. 2/0175/14, 2/0176/14, 2/0181/13, APVV 0171-10, APVV 0526-11 and ESF project 26110230097.