Comment on “Regularizing capacity of metabolic networks”

In a recent paper, Marr, Müller-Linow, and Hütt [Phys. Rev. E 75, 041917 (2007)] investigate an artificial dynamic system on metabolic networks. They find a less complex time evolution of this dynamic system in real networks, compared to networks of null models. The authors argue that this suggests that metabolic network structure is a major factor behind the stability of biochemical steady states. We reanalyze the same kind of data using a dynamic system modeling actual reaction kinetics. The conclusions about stability, from our analysis, are inconsistent with those of Marr et al. We argue that this issue calls for a more detailed type of modeling.

Figure 1

(Color online) Illustration of the construction of substrate graphs from chemical reactions (a), and our method for recreating a reaction system from a substrate graph (b).

Figure 2

(Color online) Time evolution of the average standard deviation $\Sigma$ of the flux. Standard errors are smaller than the symbol size.