In an equilibrium state, formation and dissociation reactions occur at the same rate. Therefore, concentrations of particular reagents remain constant. The ratio of products and substrates concentrations (as approximations of activities) is constant under defined conditions (pH, ion strength, temperature) and is called a reaction constant. For the reaction depicted in Eq.1. the reaction constant may be written as in Eq.3. where 𝐾 𝑑 refers to the dissociation constant. In the case of polyvalent receptor saturation, for each stage an equilibrium state is established and defined as in Eq.4. According to the geometry of phage particle pIII end, if all peptides are properly synthesised and exposed, they should not affect each other. Currently, there is no evidence that any allosteric effect might be present between peptides. Therefore, each stage dissociation constant equals 𝐾 𝑑 of the isolated TnT-peptide complex defined in Eq.3. Moreover, the cumulative dissociation constant of particular stage saturation may be expressed as in Eq.4.