  Several ionic liquids (ILs) are known to revert aggregation processes and
improve the in vitro refolding of denatured proteins. In this paper the
capacity of a particular class of ammonium based ILs to act as refolding
enhancers was tested using lysozyme as a model protein. Raman spectra of ILs
treated fibrillar lysozyme as well as lysozyme in its native and fibrillar
conformations were collected and carefully analyzed to characterize the
refolding extent under the effect of the IL interaction. Results obtained
confirm and largely extend the earlier knowledge on this class of protic ILs
and indicate Ethyl Ammonium Nitrate (EAN) as the most promising additive for
protein refolding. The experiment provides also the demonstration of the high
potentiality of Raman spectroscopy as a comprehensive diagnostic tool in this
field.
