Fig. 4.

Major and minor conformations of the bacterial phosphotriesterase. The major ‘closed’ conformation of PTE is shown in cyan, while the minor ‘open’ conformation is shown in grey (3A4J). Both conformations were modeled into the electron density of an apo-enzyme crystal. The substrate Z-chlorfenvinphos is shown docked based on known enzyme:substrate complexes (2R1N). It can be seen that in the ‘closed’ conformation, several side-chains adopt rotamers that extend into the active site, greatly reducing its volume. One of these, F132, is shown to sterically clash with Z-chlorfenvinphos in its dominant conformation but to allow binding in its minor ‘open’ conformation