In the context of protein purification, what does the term "affinity chromatography" refer to?

Affinity chromatography is a powerful technique used in protein purification, which focuses on the unique interactions between a protein of interest and a specific ligand that is immobilized on a solid support. This method capitalizes on the high specificity of these interactions, allowing the target protein to be separated from a complex mixture based on its affinity for the ligand.

In practice, a sample containing a variety of proteins is passed through a column that contains the ligand. When a protein that has a high affinity for the ligand flows through the column, it will bind to the ligand, while other proteins that do not interact similarly will be washed away. Following this, the bound protein can be eluted from the column by introducing a solution that disrupts the interaction, often by changing the pH or using a competing ligand.

This method is particularly advantageous because it allows for the purification of proteins with high specificity, minimizing the need for extensive processing or complicated procedures often required in other types of chromatography. Hence, it stands out as a highly efficient way to isolate proteins of interest in biological research and biotechnology applications.