What is the Difference Between Gel Filtration and Affinity Chromatography?

The main difference between gel filtration and affinity chromatography lies in the separation mechanisms they use. Gel filtration, also known as size exclusion chromatography, separates molecules based on their sizes by using a porous resin material. In contrast, affinity chromatography separates molecules based on their affinity for a target ligand attached to the chromatography resin.

• Gel Filtration: This technique uses gels containing beads with a known pore size to separate molecules based on their size. When a complex protein mixture is passed over the gel filtration resin, small molecules move through the bead pores, while larger molecules are excluded and flow around the beads. The separated molecules are collected based on their elution order.
• Affinity Chromatography: In this method, proteins are separated according to their binding affinity for a specific ligand coupled to the matrix material. When a mixture of proteins is passed through a column packed with a ligand-coupled matrix, only proteins that bind to the ligand will be retained. The target protein is eluted by a solution containing a solute that competes for the binding site of the ligand (or its analogue).

In summary, gel filtration chromatography separates molecules based on their size, while affinity chromatography separates molecules based on their affinity for a specific ligand.

Comparative Table: Gel Filtration vs Affinity Chromatography

Here is a table comparing the differences between gel filtration and affinity chromatography:

Gel filtration chromatography is an analytical technique that separates components based on differences in molecular weight or size. It uses a porous matrix of spherical particles as the stationary phase and elutes samples isocratically, meaning there is no need for different buffers during the separation.

Affinity chromatography is a preparative technique that depends on the affinity of an analyte to an immobilized ligand. It is used for the purification of proteins with specific binding affinity to the ligand.