Geometry optimizations of the active site isomers were carried out in both the gas phase and implicitly solvated with a dielectric value, e = 10, approximately mimicking the protein environment. Conductor-like polarizable continuum model 113 (C-PCM) solvation energies using the conductor-like screening solvent model (COSMO)-type epsilon function were used to perform implicitly solvated optimizations. As observed in prior work , the inclusion of solvent environment effects through implicit solvent alters most gas-phase geometries very little, i.e., most bond length differences are less than 0.03 Å while a few outliers have larger changes (Supporting Information Table ). Hence, we carry out further analyses only in the gas phase. All initial and optimized structures for gas-phase optimizations are provided in the Supporting Information.