Figure 1.

The coupling of highly connected metabolites. The first 15 rows and columns of M are shown for all six networks analyzed. The box and bar colors represent the network: E. coli (blue), S. cerevisiae (red), H. pylori (green), S. aureus (orange), mitochondrion (yellow), M. barkeri (brown). The box size and bar height represent the number in each particular element of M, scaled by a log transform and normalized by the network size. Larger boxes or taller bars of a given color indicate that the pair of metabolites in question participate in relatively more reactions together. Reading down the rows or across the columns gives the most connected metabolites in order, averaged over all six networks.