Protein Contact Numbers versus Sequence Length

The number of Cα-Cα contacts (upper panel y-axis) or Cβ-Cβ contacts (lower panel y-axis) versus sequence length (x-axis) for 9896 non-redundant (pairwise sequence identity <40%) SCOP domain structures collected from SCOPe 2.06. The four different columns stands for short, medium, long, all (=short+medium+long) contacts. Each point in the figure is one SCOP domain, with red, green, and blue stands for α proteins, β proteins, and others. The black straight line in each subplot is the least square fit.