Figure 4.

A small area of the active site studied (the central part in Figure 3), showing the atomic numbering used throughout this paper. Because they are the only groups required in the analysis, only the Asp25 and Asp25(′) carboxyl groups, the reactive (WR) water molecule, and the peptide area of the substrate are shown. The structure on the right corresponds to the transition state, and the straight reaction arrows reflect that the energy of this state is higher than that of the left structure. Note that the similar arrows in Figure 1 represent the overall direction from reactant to products, and hence face the opposite way.