Introduction:
Affinity chromatography is a type of liquid chromatography that separates molecules based on a specific and reversible interaction between a molecule in a mixture and a counter-molecule bound to a stationary phase.
It's a highly selective technique often used in biochemistry and pharmaceutical fields to purify and concentrate a specific molecule from a complex mixture, such as the isolation of a specific protein from a cell lysate.
Principle:
The fundamental principle behind affinity chromatography is the selective and reversible binding of a molecule (ligand) from the mobile phase to a complementary molecule (counter-ligand or affinity ligand) immobilized on the stationary phase.
This binding can be due to various interactions, including enzyme-substrate, antigen-antibody, or receptor-ligand interactions.
During the chromatographic process, the target molecule in the mixture binds to the stationary phase due to its affinity to the immobilized ligand.
Other molecules, having no or weak affinity, pass through without significant retention.
The bound target molecule is then eluted by changing the conditions, e.g., altering the pH, ionic strength, or by introducing a competing ligand.
