Figure 3.

To avoid negative concentrations in E_adapt, j₀ (Fig. 2a) is represented as an enzymatic zero-order process. (a) Fully expanded Michaelis-Menten mechanism. The rate equations together with rate constants are shown in the Appendix. To obtain robust homeostasis in A, E_set removes active E_adapt into an inactive form E_adapt^∗ under zero-order conditions with A_set given by Eq. 3. (b) Same mechanism as in panel a, but formulating the Michaelis-Menten mechanism under steady-state/rapid equilibrium conditions. Rate equations are given in the Appendix. A zip-archive containing MATLAB and Berkeley Madonna versions of the model shown in Fig. 3 A with instructions and annotation available in the Supporting Material.