Two additional models, Inactive fGln123 and Inactive Val51, were manually constructed (see SI for construction details) to analyze separately how fGln123 proximity, the Val51 backbone conformation, and the position of the oxyanion strand influence TS stabilization in the Active model. This approach is reminiscent of theozyme modeling, where residues, or functional groups, are hypothetically arranged in a truncated active site to explore catalytic contributions of individual atomic interactions and predict optimal catalytic scaffolds. In our approach, the distinct models enable us to quantify the influence of each structural difference relative to the active model separately. The oxyanion hole contributions were evaluated in each TS by estimating the donor-acceptor orbital interaction energies of the Leu85, Gly52 and Val51 𝜎 * orbitals and the Gln Oε lone pair electrons via Natural Bonding Orbital (NBO) analysis. Calculation details are found in the Computational Details section.