  Exploring the structural topology of genome-based large-scale metabolic
network is essential for investigating possible relations between structure and
functionality. Visualization would be helpful for obtaining immediate
information about structural organization. In this work, metabolic networks of
75 organisms were investigated from a topological point of view. A spread
bow-tie model was proposed to give a clear visualization of the bow-tie
structure for metabolic networks. The revealed topological pattern helps to
design more efficient algorithm specifically for metabolic networks. This
coarse-grained graph also visualizes the vulnerable connections in the network,
and thus could have important implication for disease studies and drug target
identifications. In addition, analysis on the reciprocal links and main cores
in the GSC part of bow-tie also reveals that the bow-tie structure of metabolic
networks has its own intrinsic and significant features which are significantly
different from those of random networks.
