Figure 6

Bell-shaped dose-response in the active phosphatase case (Figure2c). (a) Bell-shaped response in the zero-order regime when S _t ≫ P _t . Parameters used are: λ₋₁ = 10 s⁻¹,λ₁ = 1μ M⁻¹s⁻¹, k₁ = 1 s⁻¹,λ₋₂ = 10 s⁻¹,λ₂ = 20μ M⁻¹s⁻¹,k₂ =1 s⁻¹,λ₋₃ = 10 s⁻¹,λ₃ = 1μ M⁻¹s⁻¹,k₃ = 100c s⁻¹,κ₋₁ = 50 s⁻¹,κ₁ = 1μ M⁻¹s⁻¹,P _t = 1μ M,S _t = 10μ M. The Hill coefficient for the basic model is n _H = 2. 15. (b) Bell-shaped response outside the zero-order regime when S _t ≪ P _t : λ₋₁ =10 s⁻¹,λ₁ = 1μ M⁻¹s⁻¹,k₁ = 1 s⁻¹,λ_{− 2}= 10 s⁻¹,λ₂ = 20μ M⁻¹s⁻¹,k₂ = 1 s⁻¹,λ₋₃ = 10 s⁻¹,λ₃ = 1μ M⁻¹s⁻¹,k₃ = 100 s⁻¹,κ₋₁ = 50 s⁻¹,κ₁ = 1μ M⁻¹s⁻¹,P _t = 1μ M,S _t = 0. 1μ M. The Hill coefficient for the basic model is n _H = 1. In (a)-(b), the full line corresponds to the basic model, the dashed line is numerical results for the extended model and the dotted line shows the tQSSA approximation.