What is the Hofmeister effect?

What is the Hofmeister effect?

Hofmeister or specific ion effects describe the specific influence of different ions on some physicochemical properties of a system or on a reactive process.

Which of the following is the order of anionic salts in Hofmeister series?

In accordance of the capability of salts to stabilize proteins in solution, the classical Hofmeister ion series could be ranked. The overall order of the anion series is as follows: CO32– > SO42– > S2O32– > H2PO4– > F– > Cl– > Br– > NO3– > I– > ClO4– > SCN– (Figure ​1).

What is lyotropic effect?

Lyotropy (a portmanteau of lyo- “dissolve” and -tropic “change”) refers to concentration-dependent physical effects in solutions and often more specifically to ion-specific behavior in aqueous solutions.

How does salting in affect solubility?

Salting in refers to the effect where increasing the ionic strength of a solution increases the solubility of a solute, such as a protein. This effect tends to be observed at lower ionic strengths. The solubility of proteins usually increases slightly in the presence of salt, referred to as “salting in”.

What salt is most commonly used for protein crystallization?

Ammonium sulfate is the most widely used precipitant of the salt type. Citrate salts, due to their chelating properties, may be especially useful when the presence of divalent cations interferes with crystallization.

How does Hofmeister series work?

The Hofmeister series or lyotropic series is a classification of ions in order of their ability to salt out or salt in proteins. Early members of the series increase solvent surface tension and decrease the solubility of nonpolar molecules (“salting out”); in effect, they strengthen the hydrophobic interaction.

Which is the most common method of protein crystallization?

Vapor diffusion is the most commonly employed method of protein crystallization. In this method, droplets containing purified protein, buffer, and precipitant are allowed to equilibrate with a larger reservoir containing similar buffers and precipitants in higher concentrations.

Which salt is used for enzyme crystallization?

Sodium malonate clearly was much more successful than any other salt, resulting in the crystallization of 19 of the 23 macromolecules, almost twice as effective as the next most successful salt, which was a draw between sodium acetate, sodium tartrate, sodium formate, and ammonium sulfate (11 of 22).

How salting out is done?

The procedure consists of adding a water-miscible organic solvent to the aqueous sample followed by the addition of a suitable salt (or a mixture of salts) to induce the phase separation between the water and organic solvent, due to the salting-out effect.

What is salting out and why is it necessary in soap production?

Addition of salt to hasten or to improve the separation of soap from glycerol and weak lye during manufacture. Also, to hasten or to improve the separation of sulfated oil from the residual solution after sulfating.