Figure 10: Behaviour of the system at low concentrations of PEP as calculated by the Model II. (a) dependence of the rate of HPr phosphorylation on the PEP concentration in the absence of Pyr; (b) dependence of the stationary concentrations of the different phosphorylated EI forms on PEP concentration: 𝑍 𝑃 P E P : singly phosphorylated protein with bound PEP; ZPf: singly phosphorylated protein without PEP. Other designations are as shown on Figure 4. At the PEP concentration equal zero, all concentrations of the phosphorylated EI-forms are equal zero (not shown).