Abstract
The effect of neutral salts on protein conformation was first analyzed by Hofmeister in 1888, however, even today this phenomenon is not completely understood. In order to clarify this effect we studied changes of the secondary structure of two proteins: human serum albumin with predominantly α-helical structure and porcine pancreas -trypsin with typical -structural arrangement in aqueous solutions of neutral salts (KSCN, KCl, (NH4)2SO4). The changes of the secondary structure were studied at 23 °C and 80 °C by using the second derivative deconvolution method of the IR spectra. Our results demonstrated that the ability of the salts to stabilize / destabilize these two proteins correlates with the Hofmeister series of ions. At the same time, some exceptions were also observed. The destabilization of the native structures of both α-helical albumin and β-structural trypsin upon interaction with neutral salts leads to the formation of intermolecular β-sheets typical for amyloid fibrils or amorphous aggregates. Thus, our quantitative FTIRspectroscopy analysis allowed the further clarification of the mechanisms and complexity of the neutral salt actions on protein structures that may lead to strategies preventing the undesired misfolding of proteins.