Drummond et al. 10.1073/pnas.0500729102.
Fig. 5. PSE-4/TEM-1 double-crossover chimeras are predicted to exhibit an even higher functional tolerance to sequence change than chimeras in our experimental library. For each substitution level m, the average number of residue–residue contacts broken (<E>) is shown for the experimental b-lactamase library (squares) and double-crossover chimeras (diamonds). All substitution levels are shown with respect to the most closely related parent.