Before revision:  By this comparison, we are able to identify  some interesting general properties of protein universe, going from the confirming of a threshold size around 250 residues ( discriminating "easily foldable" from " difficultly foldable" molecules consistent with other independent data on protein domains architecture) to the relevance of contact graphs eigenvalue ordering for folding behavior discrimination and characterization of the E. coli  data.
After revision:  By this comparison, we are able to identify some interesting general properties of protein universe, going from the confirming of a threshold size around 250 residues ( discriminating "easily foldable" from " difficultly foldable" molecules consistent with other independent data on protein domains architecture) to the relevance of contact graph spectra for folding behavior discrimination and characterization of the E. coli data.