Chaotropic ions

In principle, two different mechanisms have been proposed on how the ions influence protein stability. Firstly, it has been suggested that a modification of water s structure is the origin of the Hofmeister sequence (130). It has been hypothesized that some ions kosmotropes enhance the structure that surrounds the ions, which leads to a strengthening of the hydrophobic effect and thereby stabilizes the proteins (131). However, the ions that break the stmcture that surrounds the ions ( chaotropes )... 

Oku, N., and MacDonald, R. C. (1983b). Formation of giant liposomes from lipids in chaotropic ion solutions, Biochim. Biophys. Acta. 734. 54-61. 

Ion exchange chromatography is another means to remove detergents and chaotropes from protein samples. This is one rarely mentioned, but well understood benefit of using ion exchange chromatography as a first dimension separation step in a two-dimensional LC experiment. 

Initially, the antibodies should be purified prior to prepare the immunoaffinity column. Precipitation with ammonium sulfate, ion-exchange chromatography, gel filtration chraoma-tography or affinity chromatography may be employed with the aim of antibody purification. Activated beads which are coated with bacterial proteins A or G may be used as the support material. Some parameters may be changed for the elution of the sample solution for example the ionic conditions of mobile phase may be changed or chaotropic buffers may be used [11]. 

Low inorganic ions level (stability of macromolecules, chaotropic agents, protein synthesis, etc.). 

Figure 8.6 Hofmeister series of kosmotropic and chaotropic ions.

The second attempt describes the influence of salt as an interaction of chaotropes and kosmotropes with layers of hydration on the surface of the respective ion. This interaction can be captured by measuring relative viscosity as a function of salt concentration or ionic strength (Jones, 1929) [Eq. (8.60)]. 

Here r/0 is the viscosity in salt-free medium and A and B are constants at high salt concentrations, the second term becomes irrelevant. The constant B, which is the second virial coefficient signifying ion-solvent interactions, is termed the Jones-Dole coefficient after the inventors (Jones, 1929). Chaotropes have a coefficient B which is less than zero, whereas kosmotropes are characterized by 1 > 0. 

---