Skip to main content


Fig. 2 | BMC Systems Biology

Fig. 2

From: Single molecules can operate as primitive biological sensors, switches and oscillators

Fig. 2

Two intermediates (TI) system. a Wiring diagram of the TI system. Single-modified forms (OP, PO) are physically different. b Bifurcation analysis of TI system. The graphic shows how the concentration of the catalytic molecules, OO and PP, is affected by the availability of phosphate donor (nt). We speculate that the TI system could have served as a primitive molecular sensor of phosphate donor level. Thus, TI could get into the PP form only above a critical threshold, where it remains until the phosphate level drops below a lower critical level. The stable steady state (ss) is indicated by a solid line, while the unstable steady state (us) is labelled by the dash-dotted line. See networks topology in Methods for more information about the structure. Table 2 in Methods for values of each parameter. c List of reactions. The left column shows the catalytic reactions, while the right column gives the spontaneous reactions. On top of each reaction arrow, the parameter names that affect the specific reaction are indicated

Back to article page