Fig. 3. Conformational heterogeneity.

a B-factor Z-scores for the residue at position 50 in the absence of bound 6-nitrobenzotriazole (6NT) decrease over the course of the evolutionary trajectory, while those for Asp127 do not change significantly. Z-scores of individual side-chain heavy atoms are shown as dots (values averaged over both chain A and B for all structures except that of HG3.17, which contains a single chain in the asymmetric unit), while the average Z-score for the whole side chain is indicated by the bar. Positive and negative Z-scores indicate increased flexibility or rigidity relative to the average residue in the protein, respectively. b B-factor Z-scores of each protein residue (average of all side-chain heavy atoms) in the absence of bound 6NT plotted on a model backbone for each Kemp eliminase. Thickness of the sausage plot increases with the B-factor Z-score, indicating increased flexibility. The loop formed by residues 87–90 (boxed) becomes more rigid during evolution. Source data are provided as a source data file.