assay design

There are two common assay designs when working with macromolecular interactions; direct immobilization and capturing.

With direct immobilization the ligand is covalently attached to the surface using either amine, carboxyl, carbohydrate, or thiol coupling, depending on the available reactive groups.

With capturing, the ligand is bound to the surface using another recognition molecule. Typical capturing systems include biotin/strepavidin, protein A or specific monoclonal antibodies (i.e. anti-His, GST, or IgG).