Affinity chromatography group specific adsorbents

The isolation and cleanup of biological macromolecules by means of affinity chromatography form another typical example of specific application of sample treatment. Affinity chromatography exploits specific functional properties of molecules as retardation of specific groups of solutes in the adsorption step takes place. Later on, adsorbed... 

The availability of a great variety of group-specific adsorbents in prepacked columns makes possible the combination of FPLC and affinity chromatography for the separation and purification of proteins. 

In this case, highly specific biochemical interactions provide the means of separation. The stationary phase contains specific groups of molecules which can only adsorb the sample if certain steric and charge-related conditions are satisfied (cf. interaction between antigens and antibodies). Affinity chromatography can be used to isolate proteins (enzymes as well as stmctural proteins), lipids, etc., from complex mixtures without involving any great expenditure. 

Metal chelate affinity chromatography is a kind of separation method which has, as a ligand, a metal ion. Some proteins and peptides are purified on the basis of affinity for metal ions immobilized by chelation on the adsorbents. Histidine and cysteine form complexes with the chelated metals around neutral pH. Biological proteins include many histidines as well as recombinant proteins as polyhistidine fusions for instance, His-tag proteins have a specific metal chelate affinity. The adsorbent is prepared by coupling a metal chelate ligand with an iminodiacetic acid group, which forms a chelate with divalent metal ions such as Zn2+, Cu2+, Cd2+, Hg2+, Co2+, Ni2+, Fe2+, etc. 

Many investigations in biotechnology have shown that the utilization of an interaction between specific functional groups on both the adsorber and the target molecule improves considerably the selectivity of the retention of the target substance from complex, multicomponent biological fluids (principle of affinity chromatography ). The affinity principle holds a... 

---