What is the interaction that drives binding in affinity chromatography?

Affinity chromatography primarily relies on non-covalent interactions to facilitate the binding of specific target molecules to a solid support or resin that is functionalized with a ligand. This method capitalizes on the affinity of the target protein or biomolecule for the ligand, which can be a substrate, receptor, or antibody tailored to selectively bind the analyte of interest.

Non-covalent interactions encompass a range of forces, including hydrogen bonds, van der Waals forces, ionic bonds, and hydrophobic effects. The strength and specificity of these interactions allow for the selective isolation of the target molecule from a complex mixture, while also enabling the elution of the bound molecule under conditions that disrupt these non-covalent interactions without altering the integrity of the molecule itself.

In this context, covalent interactions would imply a stronger, irreversible binding that typically is not the case in affinity chromatography, where the aim is often to allow for reversible binding and subsequent elution. Electrostatic interactions and hydrophobic interactions are specific types of non-covalent interactions; however, the term "non-covalent interactions" encompasses all potential interaction types involved in the binding mechanism, making it the most comprehensive and inclusive choice.