Antibody affinity concerns one paratope binding one epitope. A Fab fragment supplies a single-site comparison. [ref]
Glossary. Immunobiology, 5th edition, Glossary: affinity, single-site binding
In the dilute chemical equilibrium model below, smaller dissociation constant means larger antibody equilibrium occupancy at the same free antigen concentration. State the antigen, temperature and buffer solution: a dissociation constant is not a context-free score. It does not alone specify how fast attachment or detachment occurs. New to topics? Read the docs here!