The reliability of the Empirical Valence Bond (EVB) method hinges on conducting enzyme calculations relative to the same reaction taking place in a water environment, as mentioned earlier. The energetics of the reference reaction in water is based on a combination of experimental information and ab-initio data, which was detailed in our previous work and depicted in Figure . To create the reference system, we employed a Surface Constraint All Atom Solvent (SCAAS) sphere with a radius of 20 Å to solvate the system. This surface-constrained water sphere was encompassed by a 10 Å surface layer composed of Langevin dipoles, followed by the bulk solvent. Long-range electrostatic effects were treated using the local reaction field (LRF) method. The system underwent relaxation in seven sequential steps, commencing at a temperature of 5 K. Subsequently, the temperature was gradually increased up to the experimental temperature of 310 K, over an overall relaxation time of 200 ps, resulting in the generation of five distinct starting structures. For the reference system, mirroring the reacting system in water, we adhered to the same protocol as employed in the enzyme calculations. The determination of reaction free energy profiles was carried out using the EVB method, wherein, in the case of two resonance states, the ground state energy (𝐸 𝑔 ) was computed through the solution of the secular equation given by,