The Role of Cations of the Precipitant in the Interaction of Protein Molecules in the Lysozyme Oligomers in Crystallization Solutions

At the moment, the main opinion is that protein crystallization depends mainly on the the precipitant anions, therefore, there have been only few works devoted to the problem of the influence of its cations. Using the molecular dynamics method, we investigated the stability, changes in the compactness and structural transformations of lysozyme dimers and octamers in solutions with different precipitants (LiCl, NaCl, KCl and CuCl2) in order to study the contribution of cations during crystal formation in more detail. As a result, we found that cations have a rather noticeable effect on the behavior of oligomers: the higher the atomic mass of the cation, the greater the changes in the dimers structures during its dynamics and, according to the data of SAXS experiments, the lower the concentration of dimers. However, for octamers, this dependence is more complicated.