Fig 4. Behavior of the motif 2 zero-order controller (Fig 2) upon an exponential increase of k1 (left panel Fig 3 and the influence of multisite inhibition (Eq 5)).
Phase 1: the controller is at its set-point/steady state with constant k1 = 2.0. Phase 2: Response of the controller with the different n values upon the exponential increase of k1. Rate constants are: KI = 0.1, k2(max compensatory rate) = 1 × 105, k3 = 5 × 103, k4 = 1 × 103, KM = 1 × 10−6. Initial concentrations: A = 5.0 (for all n), E (n = 2) = 9.9, E (n = 4) = 0.9.