The topological structures and robustness of the protein-protein interaction networks (PINs) is studied via random graph theory. Several global topological parameters are used to characterize PINs for seven species. Good evidence by correlation analysis support the fact that the seven PINs are well approximated by scale-free networks. It is also found that two of the species' PINs are well described by the hierarchical models. In particular, it is determined that the E. coli and the yeast PINs are well represented by the stochastic and deterministic hierarchical network models respectively. These results suggest that the hierarchical network model is a better description for certain species' PINs. Furthermore, it is demonstrated that PINs are robust with respective to failure, attack, random rewiring and edge deletion perturbations.
International Journal of Artificial Intelligence Tools 15(2):309-321