Structural features of proteins as reflected by statistical scaling laws

Within this paper, statistical scaling laws for the radius of gyration with the residues number, the surface area with the probe radii and the backbone length with the interval of residues for a set of 60 proteins are revealed. The proteins belong to three different structural classes: alpha, beta and alpha plus beta class (20 proteins for each) according to the SCOP database classification, which takes into account the composition in the elements of their secondary structure. The shape and the surface roughness of proteins seem to be independent of the protein content in the secondary structure elements. On the contrary, the protein packing density shows a strong correlation with this composition