Practice question

Immunoassays like ELISA, RIA and immunoelectrophoresis all depend on reversible non covalent interactions between antibody paratope and antigen epitope involving hydrogen bonds, electrostatic forces, Van der Waals and hydrophobic interactions. No covalent bond forms, allowing equilibrium, competition and washing steps. High affinity binding is reversible and governed by law of mass action. This principle underlies quantitative measurement, displacement curves in RIA, sandwich capture and precipitation arcs. Therefore all listed immunochemical techniques share non covalent reversible binding as mechanistic basis for specificity and quantification.