5. Affinity Chromatography.

Affinity chromatography was originally developed for the enzyme purification. Now, it has been extended to immunoglobulins, membrane receptors, nucleic acids, nucleotides, whole cells and cell fragments.

It is theoretically capable of giving absolute purification from complex mixtures in a single process.

Affinity precipitation, in which the ligand is attached to a soluble carrier that can be subsequently precipitated by for example pH change.

Affinity Partition, in which the ligand is attached to a water-soluble polymer such as polyethylene glycol and which, with the ligand bound, partitions into an aqueous polymer phase that is in equilibrium with a pure aqueous phase.

In this chromatography, the most commonly used matrix are, cellulose, agarose, polyacrylamide, polystyrene, cross-linked dextrans and porous glass antisilica.

Applications of Affinity Chromatography:

1. used to purify a large variety of macromolecule such as enzymes, membrane receptors, nucleic acids.

2. Immobilized enzymes are purified.

3. mRNA can be isolated.

4. Metal chelate affinity chromatography is the logical extension technique.

5. proteins can be separated based on their molecular weight.

6. Papain and Urease can be separated.

7. It has an application in separating DNA and RNA

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