A systematic comparison with the Wild-Type (WT) of one-point mutants of bacteriophage T4 lysozyme was carried out using as difference markers the topological parameters of the protein contact networks correspond- ing to each crystallographic structure. The investigation concerned changes at the resolution level of single residue along the protein sequence. The results were correlated with (reported) changes in functional prop- erties and (observed) changes the information provided by the energy dissipation algorithm of the "Turbine" software simulation tool. The critical factor leading to significant difference among mutants and WT is in most cases associated to the sensitivity towards mutation of relatively short windows in the amino acidic sequence not necessarily contiguous to the active site.