Figure 4

Steady state requirement for elementary flux modes. In a simulation the metabolic network gradually relaxes to a steady state in which the time derivates of internal species S1, S2, and S3 are zero. The existence of weights β is calculated for flux distributions sampled from the simulation time series. For illustration purposes, existence is coded with values 0 and 0.1 for nonexistence and existence, respectively. The weights β exist (i.e. a flux distribution can be decomposed using elementary flux modes) after a steady state is obtained.