Ionic Exchange Chromatography

This is one of the most useful methods of protein purification. Depending on the surface residues on the protein and the buffer conditions, the protein will have net a positive or negative charge 

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After recovery of biomass by centrifugation, aldolase-containing cell lysates are obtained by mechanical or ultrasound cell disruption. A purification procedure is usually required to prepare a pure catalyst for synthetic purposes and to avoid the presence of any enzyme producing undesirable side-reactions. Usually, aldolases are purified from cell lysates by a combination of conventional purification steps gel filtration, ammonium sulphate precipitation, ionic exchange chromatography. 

A feature of ion exchange chromatography is, of course, that ionic solutions are used as eluants, so that the eluted species are present in an electrolyte background. The problem which now arises in the application of electrical... 

Adsorption and ion exchange chromatography are well-known methods of LC. In adsorption, one frequently selects either silica or alumina as stationary phase for separation of nonionic, moderately polar substances (e.g. alcohols, aromatic heterocycles, etc.). This mode works best in the fractionation of classes of compounds and the resolution of isomeric substances (J). Ion exchange, on the other hand, is applicable to the separation of ionic substances. As to be discussed later, this mode has been well developed as a tool for analysis of urine constituents (8). 

Ionic solutes can be separated by ion-exchange chromatography using microparticulate resins or bonded ion-exchangers based on microparticulate silica. Such separations are often achieved more easily by ion-suppression or ion-pairing techniques, which use bonded phase columns in the reverse phase mode. 

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