Figure 4.

The structure of subtilisin E showing the entropy at each position. The yellow residues are the most variable sites (2.16 < s < 3.00, greater than one standard deviation above the mean), the red residues are moderately variable (1.31 < s < 2.16, between the mean and one standard deviation), and the gray residues have below average variability (s < 1.31). Site saturation experiments should be directed at yellow positions, whereas the contiguous yellow–red regions lend themselves to cassette mutagenesis. Figure generated by using molmol (40).