Salts

Salts,, are part of the family of ‘solubility-influencing’ agents also known as precipitants. We have tried to include all the salts that you will find in our crystallization screens. If you have a particular requirement for a specific salt that you do not see here, then please contact us.

Salts are particularly important in protein crystallization in that they can control the solubility of your protein.
Protein solubility can be decreased by changing the composition of the solution, for instance by inclusion of additives such as alcohols, hydrophilic polymers and detergents. Salts also exert their influence as precipitants according to the ‘salting out’ principle. The solubility of a protein exponentially decreases as the ionic strength of the solution is increased. The rate of decrease is a function of the particular protein and ions involved.

A simple explanation for the ‘salting out’ effect is that water molecules, otherwise available for solvation of the protein, are monopolized to form bonds with the small ions, thus the salt ‘dehydrates’ the protein. When the concentration of ions becomes sufficiently high, the proteins are driven to neutralize their surface charges by interacting with one another. This interaction may result in an ordered arrangement of the proteins in a crystalline lattice.