Fig. 6. Rank (cumulative distribution) of metabolite node degree (left panel) and reaction node degree (right panel) for metabolic networks of H. pylori. The straight lines correspond to a power-law degree distribution with exponent = |slope| + 1 = 2.32. The figure illustrates that functionally different metabolites tend to cover different ranges of the degree spectrum. Reproduced with permission from the American Physical Society (Tanaka, 2005).