Fig. 2.

(a) The normalized distributions of contact density for thermophilic and mesophilic structural proteomes. The thermophilic distribution (red squares) differs from the mesophilic one (blue upward triangles) much more than does the distribution for a control set of mesophiles (blue downward triangles). A Kolmogorov–Smirnov test applied to these curves assigns a P value of 0.00027 to the null hypothesis that the thermophilic and mesophilic curves were generated from the same underlying distribution, whereas the same calculation for the two mesophilic curves leads to a P value of 0.074. (b) The arithmetic difference of the thermophilic (violet circles) and mesophilic (orange leftward triangles) curves with the control mesophilic curve in a.