affinity chromatography A biochemical technique for purifying natural polymers, especially proteins. It functions by attaching a specific ligand by covalent bonding to an insoluble inert support. The ligand has to have a specific affinity for the polymer, so that when a solution containing the ligand is passed down a column of the material it is specifically retarded and thus separated from any contaminating molecules. An example of a suitable ligand is the substrate of an enzyme, provided that it does not change irreversibly during the chromatography.
