Chromatography in general is a laboratory technique for separating specific types of chemicals from other types of chemicals in a mixture. By using chromatography, one can determine what chemicals are in a given mixture.
Affinity chromatography is a particular type of chromatography that is used on biological samples. In this process, a scientist uses a substance called a ligand to extract the desired biomolecules from the mixture. Each biomolecule has a specific ligand to which it will bond. Therefore, introducing the proper ligand into the mixture will cause only the desired biomolecule to be separated from the rest of the mixture.
Chromatography is a group of laboratory methods that are based on selective adsorption, in which components of a complex mixture can be identified and / or purified (adsorption is a surface adhesion of molecules to the surface of other substances). The method was originally used by Russian botanist Mikhail Tsvett for separation of mostly colored product , hence the name chromatography.
Affinity chromatography is a purification technique, which usually offers more than 95% purity in a single step.It makes use of a particular native or added property to isolate a target molecule.
Affinity chromatography is used more for research purposes, the molecules are separated based on specific aspects of their structure and biological activity. They are used ligands that are immobilized in a support matrix, from which is made a column, over the column being poured the sample, containing the protein of interest and which connect the ligands contained in the column, the protein is then eluted either by changing the conditions of column (change in pH or salt concentration) or by using other molecules that will compete with the molecule of interest for binding sites of ligands. Examples of ligands according to the substance of purified: substrate, inhibitor, co factor (for enzymes), antigens (antibody), sequences of complementary bases (for nucleic acids).