Figure 1

Properties of scale-free networks and network representation. a) The figure shows a network where most nodes have very low connectivities (k = 1) but two nodes have connectivities which are far higher than the connectivity of most nodes in the network (k = 12). Scale-free networks, among other networks, have this general property. b) The upper part of the figure shows a common network representation where the substrates and products of the reactions represent the nodes in the network and the enzymes represent the edges. Our network representation is shown in the lower part of the figure where the enzymes represent the nodes in the network and the substrates and products represent the edges (reaction graph).